The SL is an 8086, right? It runs at 8mhz default?

Can it be slowed down to 4.77mhz or no?

Yes the SL comes stock with an 8086 running at 8MHz, but when in slow mode it actually runs at 4MHz not 4.77. At 4MHz an 8086 is still faster than an 8088 at 4.77MHz.

I have a 50 and 54MHz crystals heading my way, and i'm curious how much more the V30HL can take. This is only possible because all the other buses are decoupled and by modding the CPU signal i'm only affecting CPU and memory. I also had to replace memory, 150ns may be fine to run at 8MHz but even a small overclock would bring memory errors.

The motherboard now has a NEC V30HL, which should be good to do 16MHz (guaranteed) and maybe a little more. The RAM is all DIP 41464 80ns, which i believe should hold fine up to 16Mhz.

Wait...the buses in this system are decoupled? Do you have any technical documentation to back that up?

Anonymous Coward wrote:

Wait...the buses in this system are decoupled? Do you have any technical documentation to back that up?

The Tandy SL tech reference manual is available to download. I haven't read it on a while, but if i remember correctly the ISA bus is derived from the 28.6 OSCI and not from the 24MHz one that normally feeds the CPU.

The manual also states that the buffer blue chip takes only 30MHz input clock MAX and it can clearly take more than that.

The floppy controller onboard chip is disabled which also would use the 28.6 OSCI btw, but since i want HD Floppy support i'm using a generic controller on and ISA slot. There's also a Lo Tech 8bit IDE adapter, which can give about 1MB/s reads.

Ran several benchmarks, games and the system was rock stable. All this because i replaced a normal V30 for a HL version and the slow 150ns RAM for 80ns. Without these 2 changes the system wasn't even stable at 9.54MHz let alone 14.

If the ISA bus isn't decoupled from the CPU the ISA cards installed should bem on their limits. Some don't even work properly in my 12MHz V20.

In about 2 weeks i'll be able to test the system at 16.66MHz and 18MHz. I'm hoping to get the same stability at 16.66 but highly sceptical that it will even boot at 18. If it does, i hope it is stable enough just to see how many dhrystones it scores in CheckIt.

would it provide slightly better playability for Golden Axe for PC?
Play as the old guy with axe, collect a magic jars, then... activates ..the magic attack.

Joey_sw wrote:

would it provide slightly better playability for Golden Axe for PC?
Play as the old guy with axe, collect a magic jars, then... activates ..the magic attack.

Believe it or not i have never played Golden Axe in my life. I imagine that if the game was very slow on a Tandy 1000 SL it will get significantly better, but i don't imagine it being fluid. That depends on how it runs on an 8MHz V30 of course. If on the other hand it was not too slow, at 14MHz it should run just fine.

Really cool system Carlos kudos! Must be really enjoyable with that extra horsepower and the tandy-specific titles...

keropi wrote:

Really cool system Carlos kudos! Must be really enjoyable with that extra horsepower and the tandy-specific titles...

Thanks Leo!!

I'm in love with this thing, i still have to try the system at 16.6 and 18MHz, but i will probably settle for 16.6Mhz, if it keeps the rock stability i've ben enjoying.

Right now, even at 14MHz it is pretty fast! TOPBENCH reports that my system is:

2.09x faster than the original IBM AT,
1.77x faster than the 8MHz AT,
1.28x faster than the IBM 5162,
1.53x faster than a Tandy 1000 TL/TX,
1.10x faster than the SEGA TeraDrive,
1.35x faster than IBM PS/1 Model 2011,
1.05x faster than a Compaq DeskPro 286.

I'm hoping to get the 16.6MHz speed, so i will still beat some other 286 systems that are above mine.

16.6MHz

Olivetti Quaderno uses V30HL @ 16MHz, which would beat your Tandy @20MHz 😀 Add some liquid nitrogen 😀
EDIT: ah OK, your Tandy uses V30HL as well, so yeah, you're faster!

Is the V30HL faster than a regular V30? I thought it just supports higher frequencies.

Anonymous Coward wrote:

Is the V30HL faster than a regular V30? I thought it just supports higher frequencies.

No, the V30HL performs exactly the same at the same clock speed as the normal V30. The HL was just a process improvement that allowed it to work with 3.3V making it very suitable for laptops. The process improvements also allowed it to clock much higher

carlostex wrote:

The HL was just a process improvement that allowed it to work with 3.3V making it very suitable for laptops.

Does that mean you also modified the Tandy to provide 3.3v to the CPU instead of 5v? Or does it require 5v for high clockspeeds?

No i didn't touch that. The HL as stated by the datasheet can operate at 3V, but its maximum operating speed will only be 8MHz.

AWESOME JOB AND POST, i am impressed to see this much detail!!

I think "fastest" XT is the Olivetti PCS86 from 1989, not 1986 as name would suggest. its a 10mhz nec v30, has 640kb main ram, it supports EMS 4.0, but has 2x 30pin sim slots onboard (they are on 16bit a bus, not 8bit bus) that can accept 2x 16mb simms,for 32mb total although i'm 99% sure even with ems 4.0 a 8086/80186/Nec v30 class cpu can only address 16mb memory. It also has has 3x full length 8-bit isa card slots on a riser, ps/2 keyboard & mouse ports, 2x each serial/printer ports, intergrated vga/cga (the pcs86 supports vga upto 640x480x16 & cga 640x400x16 oddly its the exact same as the chipset in the AT&T system in 2nd comparison of scores). it can also take a 16mhz nec v30HL as a upgrade cpu (& be made to also operate at 16.6mhz in the pcs86)

CPU to CPU i'm sure they would equal clock for clock, but the access to the 16mb of ems memory on a 16bit bus tips the scale, especially in terms of "usability". But beating a 12mhz 286...thats JUST MADDNESS...wow

** nec v30's support 8088 emulation mode, 8086 instructions, 80186 instructions & Nec's own v30 instructions... i know some XT IDE cards can take advantage of this via a bios edit/flash... i wonder how far that could take a nec v30HL in terms of "what extra can it do"
** i have read that the pcs86's onboard paradise pvga1a 256kb can be upgraded to 1024kb, but have yet to try it

BUT AGAIN AWESOME JOB AND POST, i am impressed to see this much detail!!
(edited spelling and and order, sorry)

Run Wolfensten 3D with it 😁

At 16MHz, will the integrated features also run at that speed? It seems like it wouldn't be terribly stable. ISA would run at 16MHz, and there are no 8087s that run at that speed either. I'd leave it at 10MHz.

Cyberdyne wrote:

Run Wolfensten 3D with it 😁

i 2nd that, im really interested in how this can go in terms of "usability"?
wolf3d for 8086 and maybe a lo-tech 2mb ems card? i think that wolf3d is a good usability test, darklands a torture test?

edit: when i say "usability", i mean beyond reasonable expectation for a typical or even standard upgraded tandy 1000 sl

Who needs an Amiga when you can have a 16MHz V30! 😁