Vipersan wrote on 2023-02-13, 20:53:

Took a chance and fitted my 80387 co pro in socket U69 Set jumper E20 unlinked 2-3 linked 1-2 ...and applied power allowing to b […]
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Took a chance and fitted my 80387 co pro in socket U69
Set jumper E20 unlinked 2-3 linked 1-2
...and applied power allowing to boot the setup floppy.
It did boot to the disk in A:
and the 387 was recognised.
I guess this at least verifies the chip as working....which up to now was an unknown quantity.
The 386DX is a 386DX-20 ...but my 387 is only a 387-16...
so I'm guessing a clock speed mismatch..
Will this be a problem ?
I simply dont know.
anyone ?

clock speed mismatch?
the 387 will be overclocked to 20MHz.

Thanx Coffee...I suspected as much...
Do you think 25% overclocking will damage the 387 ?
I will of course keep my eyes open for a 20mhz version but they do tend to be a bit expensive.
rgds

I recently had to deal with my mums passing..
obviously this made it impossible to continue working on this project at that time.
Dementia finally claimed her at 88 ...RIP mum.
anyway ..back to the Compaq.
I managed to obtain another 2 x proprietory simms so the on board slots are now fully populated.
Sadly only to 1mb total.
I believe it was possible to go beyond the 1mb limit but required an ISA expansion unit...which I currently dont have.
On the plus side.
I hopefully got rid of the vertical line on screen..
I'm hopeful it wont return.
I opened up the plasma screen unit ..cleaned and re-seated any connectors and heated the driver pin chip legs with flux and hot air..but only the chips relevant to that area of screen where the line appeared.

I managed to install a larger hard drive using the setup floppy
I used Type 42 which gives 502.98 free...after accepting a larger hard drive.
I had 2 to try
A seagate ST3660A which is 545mb I believe.
and a Quantum 540AT ...544 mb ?
both were recognised and allowed partitioning and formatting...
Format C:/S
But for some reason which I still dont understand...the Seagate would not boot and just hung..
Maybe an incompatibility ...or could be faulty...though Scandisk finds no errors.
The Quantum however played its part perfectly....giving me a good 500mb to install both DOS 6.22 and Win3.10.
Progress I guess...
Oh..and I now have a 1.44mb floppy in as well which makes life easier.
I also need a replacement screen retention/release button for the left side of the unit..
it is broken and only the right side button/latch holds the screen locked in place.
regards
VS

I am simply not happy after reading this snippet from the Compaq 386 manual..
>>>
Chapter 8.12 Memory Upgrade Kit
Each 1 megabyte memory upgrade kit consists of two 512 Kbyte memory modules,
which are surface mounted with four 256K x 4, 80 ns RAM chips and two
256K x 1, 80 ns RAM chips.
The memory upgrade kits are used on the system board to expand its base one
megabyte of standard RAM to two megabytes. The memory upgrade kits also
provide the memory capacity of the 1 to 2 megabyte memory expansion board.

>>>>
since I now have 4 of these proprietory simms installed fully populating the simm slots
When I first got this portable I only had 2.
these 42 pin simms are certainly non standard...but the info from the manual indicated that a total of 2mb _ should_ be possible
each simm has 4x Toshiba TC514256J-85 and 2xAAA2801J-08
This to me seems like 512k each thus 4 simms should be providing 2mb not 1mb as I thought.
So I began investigating jumper settings on the mainboard...and yes....moving E15 from pins 1/2 to E15 2/3 should enable all 4 simms to be recognised.
E16 and E17 are also memory related and are for the ram expansion card (I dont have) ..thus both E16 and E17 should remain at 1/2.
I tried this of course and sure enough the memory count at boot now climbs to 2mb (2048).
The luggable then threw up an error 160.
I inserted the setup floppy again...and running setup autocorrected the memory error.....BUT.....also reset the hrd drive controller to zero ?
This meant of course my 500mb hard drive was no longer seen....and no attempt to set back to Type 42 controller (0) was possible ?
It did however allow me to reinstall the ST3250A using type 35.
and thus possible to reboot the original install of win3.1
..which is where I currently am.
Annoyingly half the capacity of the ST3250A is not used ..it being a 214 mb hard drive of which only 100mb approx is used in this mode.
It is such a pity there isn't a setup disk image out there (at least I dont know of one) that accomodates newer or larger capacity drives.
Did Compaq never release an updated setup floppy for this machine ?
I can use more memory with a hard drive setup fudged to use half capacity ...or a larger capacity drive (fudged) but am then limited to 1mb of ram.
What a bizzare setup this machine is.
I guess the hard drives were supplied with pre-installed OS by Compaq and were a fixed 'type' ..hence the limited list to select from.
Almost proprientory by choice.
I will upload an image of a compaq proprietary 42 pin simm later if anyone is curious.
This whole thing puts me in mind of the Toshiba luggable T5200/100 Ian B conquered some time ago.
It too used proprietary simms and refused anything but Conner hard drives unmodified.
rgds

My sympathies for your Mother.

Cheers,

Thankyou Pentiumspeed...
That is much appreciated.
It does sadly bring into sharp focus ones own mortality...especially an old fart like myself.
One of the reasons I attempt these projects is to give the old grey matter a good workout.
rgds
VS

After much digging and much reading online...getting the compaq 386 to output anything from the RGBi port ...I drew nothing but blanks.
Either folk dont share this information or simply dont know ?
Anyhoo...I finally achieved my goal getting the compaq to output RGBi (CGA) after reading this

>>>>
Video output

The video hardware is a superset of CGA, with a doubled vertical resolution (640x400 rather than 640x200), outputting on an amber plasma display.

There is no font ROM. The font (8x8 or 8x16) is held in another bank of video RAM, and loaded by the BIOS at boot time.

Some I/O ports used by the video hardware are:

13C6h [r/w]
Bits 0-2: Master mode. 0=CGA 1=EGA 3=MDA Other values unknown
Bit 3: Active monitor. Set for internal, reset for external.
When an external monitor is in use, the font is assumed
to be 8x8; otherwise, it is 8x16.
Bit 6: If, when read, this is 0, then the Compaq extended video
functions (INT 10h / AX = 0BFh) are available.
17C6h [read]
Video hardware capabilities. As described in the Interrupt List:

Bit 0: 0 if CGA supported, else 1.
Bits 1-2: Reserved (1)
Bit 3: 0 if MDA supported, else 1.
Bit 4: 0 if BitBlt engine supported, else 1.
Bit 5: 0 if 132-column mode is available, else 1.
Bit 6: 0 if 640x480x256 mode is available, else 1.
Bit 7: 0 if 8-bit DAC is available, else 1.
>>>>
realising the output to an external monitor...or in my case to a scart input of a TV via a 9pin dsub to Scart converter designed by Retro Erik...and sold through Serda Shop. ...was interupt driven by setting certain bits.
This is activated by the key combination CRTL ALT < (lessthan)
BUT timing is critical it seems..
So far I have only managed this by pressing these keys simultaneously immediately after "starting MS DOS" appears on the plasma screen ..
Too early gives a keyboard error and reboot...
Too late ie once win3.1 has started the key combination no longer works.
I grabbed a couple of photos to share..
One of the windows screen .....which then appears in mono on my TV.(MDA mode ?)
I could then exit to DOS remaining in CGA mode ...and booting Paku Paku from a floppy..

I have not found a way to switch back whilst the compaq is running.
..but a power down and reboot solves this.
Apparently CTRL ALT > (greater than) is supposed to achieve this but not for me.
Maybe it is because I'm not using a genuine CGA monitor ?
Maybe Compaq cga monitors make use of the reserved pin ...pin 7 of the 9pin dsub to make the portable 386 aware a monitor is attached.
If anyone discovers more about this please let me know.

Activating an external CGA monitor does of course turn off the plasma screen....the compaq portable does not support dual display mode.
regards
VS

For now I have gone as far as I can with my second Compaq III...the 286 version..
Keyboard cable replaced...1.2mb floppy replaced with a 1.44 mb ......
Hard drive replaced with compact flash..
Math co processor fitted. (287)
LeFlash XTIDE bios installed in the spare empty sockets.
Damned shame I'm restricted to base memory...but it would appear a propriatory ram expansion board is needed to go beyond this limit.
Chances are I'll never find one.
Unobtainium.
Fingers crossed that someone much smarter than me will one day reverse engineer this add on...so it can live again.
These lovely orange gas plasma luggables do seem to be getting more popular with retro geeks.