Recent content by sergey

I'd appreciate a pointer to this odd behavior. The best approach would be filing an issue in GitHub repo.

The 8088 BIOS has an integrated floppy support that pretty much does everything that Multi-Floppy does, except of supporting two FDCs and more than 2 drives. It doesn't include Floppy BIOS extension, unless you specifically installed that for whatever reason. The 8088 BIOS version 1.0.0 already...

Hi, I wanted to let you know that I released a new version of Multi-Floppy BIOS - v2.7. The main improvement in this version is implementing delays using 8253/8254 PIT channel 0 counter. This algorithm works for both AT class and PC/XT class machines. This also fixes the issue where the...

@pkhoury Xi 8088 is not a 16 bit board. The data bus is still 8 bit. The 16-bit portion of the board contains additional IRQs and non-latched A17-A19 addresses, that some VGA cards, CL-GD542x particularly, might need. With that said, some 16 bit ISA cards will operate in 8 bit mode, this...

They last years ;) How much would depend on how much time the computer is turned on, in which case the RTC will be powered by the power supply and won't be not consuming battery. MC146818 RTC consumes about 50 uA, the original battery is 2 Ah, so discharge time will be around 2/0.00005 = 40000...

@simmiv : Great job on repairing your Compaq! Where did you get a replacement keyboard cable? Mine starts to disintegrate, and I'd need to replace it at some point. Also, FYI, I designed a replacement module for Compaq III battery. It has the advantage of using replaceable CR2477 battery...

I am wondering if people here would be interested in Micro 8088 kits? Possibly the following options: 1. Micro 8088 PCB + chipset - I already did this in the past, and it was some interest. $30 + shipping 2. Micro 8088 PCB + chipset + the pre-programmed Flash ROM and the MCU for the on-board...

You can try that. But in this case, obviously, you won't have the CF card support.

@Betamax80 I am not closely familiar with the PicoMEM board. Are you not seeing any PicoMEM BIOS output at all? Or you can't boot from it? The 8088 BIOS searches the upper memory (D0000-F8000) for BIOS extensions in ascending order. It might be possible that if you swap the addresses of XUB and...

Thank you! That's very useful. It looks that my analysis of the BIOS was correct :) Does it provide any information on how to turn on and off the Caps Lock and Num Lock LEDs? Also it says that the key 84 (num pad Enter) is reprogrammable. Any information on how to do that?

This probably needs to go to the 386/486-based Systems thread

That would be valuable. For my effort, at least the description of the keyboard interface and related schematic would be indispensable

Well, thanks for the help I guess ;) I did disassemble the POST part of the BIOS. Indeed, it appears that the system uses 8251 USART to communicate to the keyboard. The USART's data register is mapped to I/O port 60h, same as the keyboard port on IBM PC/XT and AT, but it allows a bi-directional...

The DMA controller on the PC and XT doesn't use RQ/GT protocol... Instead, when there's a DMA request, the wait logic generates wait states, isolates the CPU from the bus, and lets the DMA do its business. Some clones, particularly chipset based ones, such as FE2010A, PT8010AF, 82C100 do use...

ExPLIT got a bit of a puzzle for me... His colleague has an Ericsson PC, and they tried to run my 8088 BIOS on it. Everything seems to work fine, except of the keyboard. I partially disassembled the INT 9/IRQ1 interrupt handler, and apart from typical PC/XT interaction with the 8255 PPI I/O...