U51 74F74 Fast D-type flip flops, divide 30 MHz to 15 MHz U41 74F157 Fast multiplexers for SRAM MA22-20 U35 74F157 Fast multiplexers for SRAM MA19-16 U43 74F157 Fast multiplexers for SRAM MA15-12 U39 74LS393 Counter divides 15 MHz by 256 U50 74LS245 SRAM D15-8 buffer U57 74LS245 SRAM D7-0 buffer U45 74LS245 DRAM MD15-8 buffer U46 74LS245 DRAM MD7-0 buffer U52,53,54,55 74LS244 Bus signal buffers
U1-32 ? DRAM, 256K x 4-bit U36,42,44 CY7C128 SRAM
U33 PAL20L8 SCSI logic U34 PAL20L8 SMMUX Multiplexer MA8-5 (4 bits) U38 PAL20L8 SMMS Memory U40 PAL20L8 SMMLX Multiplexer MA4-0 (9 bits) U58 PAL20L8 SMBI Bus Interface U46 PAL20R8 SMCAS CAS decoder U47 PAL16R8 SMMT Memory Timing U49 PAL20L8 SMSR Static RAM controller
U37 5380 SCSI controller
Base address = ffde00
.
00 : Data 08 : Initiator command 10 : Mode 18 : Target command 20 : Current bus status 28 : Bus and status 30 : Input data 38 : Reset parity and interrupts.
00 : DMA output 30 : DMA input 80 : DMA output with EOP b0 : DMA input with EOP.
f80000 - ffffff : MMU translation and history RAM.
000000 - 0fffff : 1st Megabyte of RAM 100000 - 1fffff : 2nd Megabyte of RAM 200000 - 2fffff : 3rd Megabyte of RAM 300000 - 3fffff : 4th Megabyte of RAM.
  | RAS | ||||||
1 | 0 | ||||||
CAS | 0 | 1 | 9 | 17 | 32 | 000000 | Base |
1 | 2 | 10 | 18 | 31 | 080000 | ||
2 | 3 | 11 | 19 | 30 | 100000 | ||
3 | 4 | 12 | 20 | 29 | 180000 | ||
4 | 5 | 13 | 21 | 28 | 200000 | ||
5 | 6 | 14 | 22 | 27 | 280000 | ||
6 | 7 | 15 | 23 | 26 | 300000 | ||
7 | 8 | 16 | 24 | 25 | 380000 | ||
  | 15-12 | 11-8 | 7-4 | 3-0 |   | ||
Data bus bits |