VOGONS


First post, by jesolo

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I recently came into possession of this PC:

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Sperry XT
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I haven't been able to find much about this PC, only that it is a 100 % IBM compatible PC running at 7.16 MHz.
Apparently, there is a switch somewhere to select turbo mode and normal mode (haven't found it yet 😀).

This PC also has a colour monitor (model 3584-01), which is one of the main reasons why I bought this PC, since I've been looking for a colour CGA monitor for a while now.
However, when I power down the PC, the monitor displays this image (I then have to also switch off the monitor):

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Colour monitor after switching off
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Is this "normal" for an older monitor of this type?
If I let the PC stand for a while (say a day or two) and then power up the PC, the monitor initially has some "jitter" which then stabilises as it warms up.
What could be the cause of this and how must I address this?

Any other information about this PC is appreciated (manuals, documentation), etc.

Last edited by jesolo on 2018-01-10, 08:40. Edited 2 times in total.

Reply 1 of 16, by derSammler

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For CGA monitors at least, this is normal. They show a bright picture when no video signal is present. That's why you normally connect the power cord of the monitor to the PSU of the PC. This way, it only gets power when the PC is on.

Reply 2 of 16, by jesolo

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derSammler wrote:

For CGA monitors at least, this is normal. They show a bright picture when no video signal is present. That's why you normally connect the power cord of the monitor to the PSU of the PC. This way, it only gets power when the PC is on.

Yes, that makes sense.
If anyone does perhaps have some documentation related to this PC, then it will be helpful as I would like to figure out what all the functions of the various jumpers & DIP switches are for.

Last edited by jesolo on 2018-01-10, 08:41. Edited 1 time in total.

Reply 3 of 16, by jesolo

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Update:
The same PC was also sold under the Leading Edge brand name as their Model M (MP-1676L).
I was able to find the layout of that motherboard: http://arvutimuuseum.ee/th99/m/I-L/30486.htm

Reply 4 of 16, by montfenn

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Are you still looking for information about this Sperry PC? I have one like it and have the manuals for it. It has been packed away in a box for a number of years now. If I remember correctly, there is a set of switches on the back at the bottom and one of them sets the CPU speed.

Reply 5 of 16, by jesolo

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montfenn wrote on 2020-07-17, 14:50:

Are you still looking for information about this Sperry PC? I have one like it and have the manuals for it. It has been packed away in a box for a number of years now. If I remember correctly, there is a set of switches on the back at the bottom and one of them sets the CPU speed.

Thank you very much. I managed to find the information I was looking for.
Scanned copies of the manuals would be nice, but I imagine this will be a daunting task. Perhaps just the part of the manual (when you can find the time) of the function of each of the switches on the motherboard as well as at the rear.

Also, any information about any slots on the motherboard that is not the standard ISA slot (there appears to a pinout for a memory expansion unit).

Reply 6 of 16, by akula65

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I used to have one of these machines. Got it new around 1984-1985. I gave it to a friend a number of years ago.

If memory serves, the Sperry graphics adapter consisted of two long cards connected by a cable. The graphics adapter was probably unique because it supported resolutions and colors that were intermediate between CGA and VGA. The maximum resolution was 640x400, and the maximum number of colors was 16. The version of GW-BASIC that shipped with it actually had support for these maximum resolution and color values in the graphics routines. I got fed up with the pokey BASIC and reverse-engineered the graphics. If you are familiar with Peter Norton's description of how graphic modes are set in "Programmer's Guide to the IBM PC," the Sperry is just an extension in that you used higher-valued arguments to put it into the higher resolution/color modes. I was able to create assembler/Pascal/C graphics routines that were twenty times as fast as GW-BASIC.

Sperry offered a Reference Manual that was on a par with that provided by IBM for their PC.

Sperry also had an PC AT clone as well.

Reply 7 of 16, by jesolo

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akula65 wrote on 2020-07-17, 17:27:
I used to have one of these machines. Got it new around 1984-1985. I gave it to a friend a number of years ago. […]
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I used to have one of these machines. Got it new around 1984-1985. I gave it to a friend a number of years ago.

If memory serves, the Sperry graphics adapter consisted of two long cards connected by a cable. The graphics adapter was probably unique because it supported resolutions and colors that were intermediate between CGA and VGA. The maximum resolution was 640x400, and the maximum number of colors was 16. The version of GW-BASIC that shipped with it actually had support for these maximum resolution and color values in the graphics routines. I got fed up with the pokey BASIC and reverse-engineered the graphics. If you are familiar with Peter Norton's description of how graphic modes are set in "Programmer's Guide to the IBM PC," the Sperry is just an extension in that you used higher-valued arguments to put it into the higher resolution/color modes. I was able to create assembler/Pascal/C graphics routines that were twenty times as fast as GW-BASIC.

Sperry offered a Reference Manual that was on a par with that provided by IBM for their PC.

Sperry also had an PC AT clone as well.

You might be thinking about the Olivetti M24 (or AT&T 6300)?

Last edited by jesolo on 2020-07-19, 20:11. Edited 1 time in total.

Reply 9 of 16, by montfenn

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Yes, on my PC the motherboard has 512K built in and a slot where an extra 128K can be added to make it up to 640K. Mine is one of the later models, the earlier ones had less built in memory and the add on memory modules were different.

This was my first computer. The place where I was working had a Sperry Univac 1100 mainframe, which meant that staff were able to purchase Sperry equipment at a price with a very good discount. While IBM were the most popular type of mainframe around, there were a few Sperry sites in SA. Some were Natal University, Natal Technikon, UCT, NBS (Natal Building Society) and KWV (a wine company in the Cape). Natal University had both a Sperry Univac and an IBM mainframe, the IBM was used for the the admin systems and the Univac for teaching and research. One interesting mainframe in Durban in the 1980s was the CDC Cyber at the racecourse. They required a powerful number cruncher to process the horse race results and the betting system.

My PC has a monochrome monitor. CGA and the Sperry Hi-Res were the other options. The high resolution monitor was Sperry specific, and was being produced by them before EGA became available and was higher resolution than EGA. And yes, the high resolution controller card took up two slots on the motherboard, while the monochrome and CGA used only one. A colour screen was beyond my budget when I bought mine.

Sperry was bought by Burroughs in the late 1980s and the merged company became Unisys

Reply 10 of 16, by montfenn

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I have a copy of the Technical Reference. I have attached a table from it showing the functions of SW3 at the back of the computer.

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Reply 11 of 16, by Horun

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montfenn wrote on 2020-07-18, 10:42:

I have a copy of the Technical Reference. I have attached a table from it showing the functions of SW3 at the back of the computer.

Excellent ! Can you post pictures of the other two switch (sw1 and sw2) functions ?

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor.

Reply 12 of 16, by montfenn

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Switch Settings (Appendix E of the Technical Reference).

There are 3 banks of switches. SW1 and SW2 are on the motherboard and SW3 is at the back of the computer.

SW1

1 Compatibility

2 Memory

3 Compatibility

4 Compatibility

5 Monitor

6 Monitor

7 Diskette Drives

8 Diskette Drives

SW2

1 Memory

2 Memory

3 Memory

4 Memory

5 Compatibility

6 Compatibility

7 Compatibility

8 Compatibility

SW3

1 Loading OFF Repeated H/W Self Test ON Normal Loading

2 Monitor OFF Hi Res ON Medium Res

3 Compatibility OFF Disable Advanced Features ON Normal Operation

4 OFF X-ON X-OFF Printer ON Non X-ON X-OFF Printer (RS-232)

5 OFF Memory Check During Loading ON No Memory Check During Loading

6 8087 speed OFF 5 ON 8

7 8087 OFF no 8087 ON 8087 installed

8 CPU Speed OFF 4.77 ON 7.16

Memory Installed SW1 and SW2

256 [1] ON [3] [4] [5] [6] [7] [8] = ON OFF OFF ON [5] [6] [7] [8]

384 [1] ON [3] [4] [5] [6] [7] [8] = ON OFF ON OFF [5] [6] [7] [8]

512 [1] ON [3] [4] [5] [6] [7] [8] = ON OFF OFF OFF [5] [6] [7] [8]

640 [1] OFF [3] [4] [5] [6] [7] [8] = ON OFF ON ON [5] [6] [7] [8]

Display Monitor SW1 and SW3

Medium, High or Colour (40x25) [1] [2] [3] [4] OFF ON [7] [8] = [1] [2] [3] [4] [5] [6] [7] [8]

Medium, High or Colour (80x25) [1] [2] [3] [4] ON OFF [7] [8] = [1] [2] [3] [4] [5] [6] [7] [8]

Monochrome [1] [2] [3] [4] OFF OFF [7] [8] = [1] [2] [3] [4] [5] [6] [7] [8]

Medium Resolution [1] [2] [3] [4] [5] [6] [7] [8] = [1] ON [3] [4] [5] [6] [7] [8]

High Resolution [1] [2] [3] [4] [5] [6] [7] [8] = [1] OFF [3] [4] [5] [6] [7] [8]

Diskette Drives

SW1

1 Drive switch 7 and 8 ON

2 Drives switch 7 OFF and 8 ON

Always OFF (Ref Figure E-8 on Page E-13)

SW1 1, 3 and 4

SW2 5, 6, 7 and 8

These are labeled as Compatibility in other figures and tables

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Reply 13 of 16, by jesolo

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montfenn wrote on 2020-07-18, 10:27:
Yes, on my PC the motherboard has 512K built in and a slot where an extra 128K can be added to make it up to 640K. Mine is one o […]
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Yes, on my PC the motherboard has 512K built in and a slot where an extra 128K can be added to make it up to 640K. Mine is one of the later models, the earlier ones had less built in memory and the add on memory modules were different.

This was my first computer. The place where I was working had a Sperry Univac 1100 mainframe, which meant that staff were able to purchase Sperry equipment at a price with a very good discount. While IBM were the most popular type of mainframe around, there were a few Sperry sites in SA. Some were Natal University, Natal Technikon, UCT, NBS (Natal Building Society) and KWV (a wine company in the Cape). Natal University had both a Sperry Univac and an IBM mainframe, the IBM was used for the the admin systems and the Univac for teaching and research. One interesting mainframe in Durban in the 1980s was the CDC Cyber at the racecourse. They required a powerful number cruncher to process the horse race results and the betting system.

My PC has a monochrome monitor. CGA and the Sperry Hi-Res were the other options. The high resolution monitor was Sperry specific, and was being produced by them before EGA became available and was higher resolution than EGA. And yes, the high resolution controller card took up two slots on the motherboard, while the monochrome and CGA used only one. A colour screen was beyond my budget when I bought mine.

Sperry was bought by Burroughs in the late 1980s and the merged company became Unisys

Thank you for all the information provided - was indeed very insightful and helpful.

As a matter of interest - after I acquired the PC in this thread, I managed to get hold of another Sperry model (just the case) from an e-Waste facility, but that one isn't posting.
I discovered that the internal modem (some very old Rockwell with some type of transformer attached to it) was causing a short and, as soon as I unplugged it, the motherboard booted up, but still wouldn't post.
As I recall, I then tested the motherboard with a the SuperSoft Landmark Diagnostic ROM and could see that one of the memory chips in bank 0 (which just happens to be soldered to the board) is faulty - this will require me to desolder the relevant one in order to allow the PC to boot.
However, what is interesting about this particular PC is that it has the external memory module plugged onto the motherboard, but it only adds up to around 512K of RAM (when I counted the memory chips' sizes).
I've attached a top down picture of the (working) PC in this thread - if you look closely, just above the barrel battery, you can see the 30-pin connector for the external memory module. Fortunately for me, on this working PC, it came with an external (after market) memory expansion card that brings it up to 640K RAM.

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Reply 14 of 16, by montfenn

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Your Sperry is nice and clean and in good condition. Not the case with mine, it has dust, rust and cobwebs. I cleaned out the cobwebs and some of the dust, but could not get it to work. The fan in the power supply starts up, it beeps but then makes no attempt to read the diskette drive to look for an O/S to load. The monitor won't turn on, so I can't see if there is any error message.

Mine is a model 3070-09. I have attached a picture of the added memory card.

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Sperry 128K Memory Add On
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Reply 15 of 16, by jesolo

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montfenn wrote on 2020-07-20, 10:21:
Your Sperry is nice and clean and in good condition. Not the case with mine, it has dust, rust and cobwebs. I cleaned out the co […]
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Your Sperry is nice and clean and in good condition. Not the case with mine, it has dust, rust and cobwebs. I cleaned out the cobwebs and some of the dust, but could not get it to work. The fan in the power supply starts up, it beeps but then makes no attempt to read the diskette drive to look for an O/S to load. The monitor won't turn on, so I can't see if there is any error message.

Mine is a model 3070-09. I have attached a picture of the added memory card.

Label.jpg

MemBoard.jpg

I just checked now and my other (non-working) one is also model number 3070-09. Maybe I misread the memory total.
First try unplugging any additional expansion cards that are on the motherboard (except for the graphics card).
If that doesn't work, try the minimum diagnostic test (to see if you don't have a short somewhere on your PSU). As I recall, the connectors of the Sperry PSU are a bit small, but I did manage to get my multimeter in there to test the voltages of the PSU.

If you have access to an EEPROM burner and some spare EEPROM's, burn a copy of the SuperSoft/Landmark Diagnostic ROM - available here: http://www.minuszerodegrees.net/supersoft_lan … dmark%20ROM.htm
I've used it on a couple of occasions and it definitely helped me to narrow down the errors on my old XT boards. Sometimes, unfortunately, it's not as simple as replacing a faulty memory chip. You then need access to an oscilloscope poke and prod more, but I that's beyond my technical skills. Luckily, I have some friends that are.

Reply 16 of 16, by montfenn

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Thanks for your suggestions. I have a multimeter, but not much else. I found an ISA VGA card and put that in so that I could connect a working monitor to it. Still, nothing appears on the screen. I have put it back in the box it was in, maybe I will try again with it some other time.