Re: PicoMEM : Pi Pico on ISA, with full Memory and I/O bus access
Posted on 2024-03-26, 16:10
OK thanks FreddyV, although I am not too familiar with Discord, I will join the group and ask specific questions again.
Re: PicoMEM : Pi Pico on ISA, with full Memory and I/O bus access
Posted on 2024-03-24, 01:21
I have an interest in retro hardware and have been experimenting with replicating the original 8088 based PC on a set of PCBs for my own fun and education. This is a very interesting card, in that I understand that it can replicate the floppy drive? My design is simplified in that I did not …
Re: Bought these (retro) hardware today
Posted on 2023-02-27, 17:43
I visited the "Retro Computer Sale" which took place at the Centre for Computing History this Sunday (26-Feb-2023) in Cambridge. That's Cambridge, England BTW! It's a small museum which has quite a number of exhibits relating to computer history in the UK. It is also "hands on" in that you can play …
Re: USB ISA cards?
Posted on 2023-02-27, 17:13
Want to order one on AliExpress but I see that there are 3 different versions (see picture). First one is the bugged one. But what about the second and third one? The first 2 are about the same price. The 3rd one is about 50% more expensive. Anyone got any idea which one is the 'best'? The top is …
Re: 80486 BIOS image collection
Posted on 2022-04-14, 15:59
#117 Manufacturer/Identifier: unknown Chipset: ALI M1429G/M1431 BIOS/Version: PhoenixBIOS Version 4.03 (graphical) Filename ALI M1429G-M1431 unknown.JPG File size 1.9 MiB Views 1997 views
Re: 80486 BIOS image collection
Posted on 2022-04-10, 23:32
#116 Manufacturer/Identifier: unknown Chipset: ALI M1429G/M1431 BIOS/Version: AMI 40-01MS-001169-00101111-080893-ALI1429G-F Filename MS4131-G whole motherboard.JPG File size 1.84 MiB Views 2019 views
Re: 80486 BIOS image collection
Posted on 2022-04-10, 23:25
#115 Manufacturer/Identifier: 3486UC-L4-V6 Chipset: UM82C481AF/UM82C482AF/UM82C206L BIOS/Version: AMI 40-0100-D81281-00101111-070791-UMC480A-F Filename 3486UC-L4-V6 whole motherboard.JPG File size 1.95 MiB Views 2023 views Filename 3486UC-L4-V6 id under sticker.JPG File size 271.96 KiB Views 2023 …
Re: ST 486 CPU - just why do 486 motherboards have all those jumpers for CPU selection?
Posted on 2022-03-31, 20:21
OK thank you. I will try this setting on the Chicony board. Fingers crossed that I have more success than with the first two 486 motherboards.
ST 486 CPU - just why do 486 motherboards have all those jumpers for CPU selection?
Posted on 2022-03-31, 20:09
There are a couple of reasons for my question 1) I bought a ST 486 CPU, because of sentimental reasons, but it hangs when tried in either of my two 486 motherboards. One time it did boot into DOS. 2) I recently mistakenly bought a new wrong 486 motherboard (I meant to buy one of a similar price from …
Re: GBS8200 Video Converter for CGA/EGA on VGA monitor
Posted on 2022-03-29, 16:30
Here is my recent experiment with the GBS-8200 and CGA from an ISA card. I bought the GBS-8200 a few years ago for the purpose of using with an Atari ST. I had lots of problems and never got it to display anything but a highly corrupted noisy picture. I was aware of the necessity to decrease signal …
Re: 8042 operation and command set
Posted on 2022-03-28, 14:23
I'm pretty sure that is a AMI MEGAKEY rev F which does support PS/2 mode OK thanks, that's a tantalising piece of information ! I do intend to re-try PS/2 mode now I have discovered the "power supply" issue, which likely affected the previous attempts to operate the chip in PS/2 mode. I did a quick …
Re: 8042 operation and command set
Posted on 2022-03-22, 19:46
Firstly a possibly useful piece of advice (IOW don't make the same mistake as me!). If connecting a 5V USB powered arduino to some other circuity, measure the VCC voltage across this circuitry, and if this voltage less than around 4.7V, then power it from some other 5V supply. My circuit was sort of …
8042 operation and command set
Posted on 2022-03-20, 17:52
I did check but no other threads seemed similar. I have been working on a IBM PC-like 8088 PCB. I have modified the Tandy1000 BIOS to work on my board. My board has a 8255 PPI for keyboard but not the usual TTL circuitry. Consequently I was interested in how I might interface a keyboard (and mouse?) …
Re: 486 motherboard schematics
Posted on 2022-03-20, 13:13
Hi @Horun, many thanks for the info. Just FYI, I am working on a separate project where I have interfaced a 8042 (marked AMIBIOS) to an Arduino Nano. Consequently I have downloaded all the information on the 8042 and clones that I can find, so I recognise the PDF which you linked. I have already …
486 motherboard schematics?
Posted on 2022-03-19, 22:22
I now have a number of 486 motherboards. One was a mistaken purchase - selected the wrong board on Ebay :-( Are there any schematics out there? They can suffer from battery damage. I am particularly interested in the keyboard connector to 8042 keyboard controller wiring and also the battery backup …
Re: Looking for info about this card (CGA - III / P)
Posted on 2022-03-13, 22:14
This card has almost identical layout to mine, however doesn't have the extremely useful set of probe points just above the ISA fingers, even though the layout has the exact layout space to put them there! The light pen connector is populated. The character set ROM has been replaced with a socketed …
Re: Looking for info about this card (CGA - III / P)
Posted on 2022-03-13, 21:59
The bank of resistors between the UDL chip and the jumpers are for creating a video signal from the CGA video outputs (R,G,B,Intensity, Hsync and Vsync). The 3 non 47k resistors in the other bank are also part of the video circuit. TR2 is configured as an emitter follower to drive video out on the 2 …
Re: Looking for info about this card (CGA - III / P)
Posted on 2022-03-13, 21:51
Found this thread while trying to find out about my own old CGA card. VDL CGA ISA card - reduced.JPG Reason for wanting to find out more is that I have just bought a faulty 8088 motherboard from an Ebay seller (UK). GIven my recent interest in this old uP I thought that it would be interesting to …
Re: USB ISA cards?
Posted on 2021-12-07, 21:13
There might be several versions of this board. Mine has the CH375B, socket for 32x8 EPROM, 74LS125, 74LS139 and 74LS138. The ROM chip select address is not fully decoded (A19 and A18 are not connected). The board whose schematics are pointed to on VCF uses a PAL/GAL16V8 for the decode rather than …
Re: USB ISA cards?
Posted on 2021-12-07, 18:35
EMM Computers designed an XT clone that boots from USB using a CH376S module. The code for the option ROM is here . Oooh! Thank you for the pointer. I follow EMM on YouTube. HIs 8088 based projects are super interesting and very inspirational! Just FYI, he also sells his PCBs on Ebay (well at least …
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