Hi Matt, because of the size of the 80286 and definitely 80386, the only thing I can get on to those boards besides the CPU are boot EEPROMs. So the MSDOS board will indeed be very useful. I don’t anticipate a V2 of the board any time in the near future. BTW, the EPROM pair of sockets are not needed with our CPU boards but are there for people that have other CPU boards without or limited, onboard PROMs.
The MSDOS support board will replace the PIC-RTC board
and PROM board
The MSDOS board has a much faster decoding circuit than the more generalized 8/16 bit PROM/RAM board. I’m sorry I did that board that way, its far too complex/convoluted for its own good.
Note however (as described in the above link), the MSDOS board will NOT recognize Z80 interrupts, only Intel 8086 and above, ones.
The 8086 Monitor I wrote completely integrates the CMOS clock so MSDOS automatically gets time and date for file stamping etc.
I have written the corresponding clock driver for the Z80 monitor and CPM+ but have not updated the S100Computers site yet.
John Monahan Ph.D
Will the "MSDOS Support board" also be necessary or at least very useful for the 80286, 80386 etc. boards planned for the future? Or is it better to wait for a V2 of this board for those?
Sorry guys for the delay. (Just returned from a 7 day business trip to Ireland).
The “MSDOS Support board” is a catch all S-100 board to make the S-100 system appear as an IBM-AT in terms of hardware for MSDOS. It’s not 100% because of space limitations, but it has the Dallas CMOS RTC (with its onboard RAM – most critical), one 8259A Interrupt controller (and LED bard showing which interrupt line is triggered), an onboard (if need EEPROM up to 256K 16 bit wide), the Intel 8254 triple counter and support circuitry for sound (as in AT) and a wait stare generator circuit that can be addressed anywhere as a hole in the 16M address space to take care of slow RAM with a very fast CPU (eg Video RAM). Have the prototype board working for past month. Andrew is doing the final “commercial quality board”. Will try and write it up on S100computers.com within the next week.
Just assembled our recent 8086 board. Works great, no problems. I run it at 9MHz with MSDOS 4.01 & CPM86+ (2 I/O wait states). Have had it up to 10.5MHz but that’s pushing it for other boards.
For those currently building the board. No changes what so ever the only error is the silk screen labels on the board for I/O and EEPROM wait stares were switched. Again I hope to write up a detailed step by step list of instructions within the next few days. Stay tuned.
John Monahan Ph.D
Hi Kipp! Thanks! The S-100 MS-DOS Support board is a basically the guts of a PC/AT without the CPU or RAM. This board will allow for a highly compatible PC/AT S-100 system to allow the use of MS-DOS, CP/M-86, and FreeDOS in a highly compatible fashion. Maybe John will comment further on this project and shed some light on his efforts.
The S-100 Super VGA is a GD5420 implementation on the S-100 bus. It is highly experimental and in development right now.
Thanks and have a nice day!
You can put me in for whatever msdos support is, and super VGA.