PICPIT

PCB

WARNING! These boards are still very early models and likely contain bugs. They've been observed to work with either no modification or with minor modification (like adding a pullup resistor) during the soldering stage, but be aware that they might not work directly "out of the box" for you or present a risk of something breaking.

Minimal 8088 8 bit ISA board

This board is slightly custom. Signals INTAK and INT have been routed through DRQ2 and DACK2 to allow external PIC-board in the BUS, equally HLDA and HOLD have been routed through DRQ3 and DACK3 to allow external DMAC-board in the BUS. These customizations mean that DMA channels 2 and 3 cannot be used normally. The board will boot when RESET jumper is connected being initially disconnected during power-up. There are 3 other jumpers for allowing operation with or without PIC and DMAC. Can boot into DOS with suitable BIOS (v2). Tested with 8 MHz V20.

Minimal Adlib compatible 8 bit ISA board

This board has its own oscillator and thus requires neither CLK or OSC to be present in the BUS.

Minimal OPL3 compatible 8 bit ISA board

This board requires OSC (14.31818 MHz) signal present in the BUS.

Minimal 512 KB 8 bit ISA RAM board

This board is configured to occupy 0x00000-0x7FFFF.

Control 8 bit ISA devices through passive backplane using Raspberry Pi (14.31818 MHz oscillator is included, MEMW/MEMR/IOW/IOR are supported, no IRQ or DMA)

Board with 8259 Programmable Interrupt Controller and 8254 Programmable Interval Timer (there is wrong 74LS93 chip in place of 74LS92 in the picture as I didn't have the correct chip at the moment of testing, 74LS93 is decade divider whereas this board requires octal divider so the PIT ran at slightly lower frequence in this test than normally).

Example of "everything" in a backplane, early video https://www.youtube.com/watch?v=vcOmHcExV3M