7 Feb
2023
7 Feb
'23
9:25 a.m.
Hello,
I could use some help making sense of the VAXstation ROM images.
A set is provided here: https://www.9track.net/roms/
The two .bin files are each one halfword of a 16-bit wide ROM for the
68000 display processor. I checked it, and it's fine.
My problem is with the Bit Blit Accelator. The board has four Am2901
bitslice processors to make up a 16-bit custom blitter. The information
I have is that the microcode is 57 bits wide and there should be 1024
words. However, this is not a great match for the rest of the ROM
images.
Some of the BBA ROMs seem to be bit masks, presumably useful for
rendering graphics. But none of them seem to match what I'd expect to
see for a 57x1024 microcode.
Here are the sizes, in bits, of the ROMs:
Bit Blit Accelerator (BBA)
23-066K3.jed 2048
23-067K3.jed 2048
23-068K3.jed 2048
23-069K3.jed 2048
23-076F4.e32 16384
23-077F4.e65 16384
23-077J5.jed 2048
23-078J5.jed 2048
23-354A1.e33 256
23-355A1.e66 256
23-356A1.e77 256
23-357A1.e85 256
Display Processor Module (DPM)
23-020L1.jed 3553
23-021L1.jed 3553
23-022L1.jed 3553
23-023L1.jed 3553
23-024L1.jed 3553
23-025L1.jed 3553
23-288E4.bin 65536 68000 code in these two.
23-289E4.bin 65536
7 Feb
7 Feb
9:32 a.m.
Given 16 bit wide ROMs, I would expect the microcode width to be rounded up to a multiple
of that, so 64 bits, which means the expected ROM size is 64k bits. That matches two of
the ROMs you mentioned.
paul
On Feb 7, 2023, at 12:25 PM, Lars Brinkhoff via cctalk
<cctalk(a)classiccmp.org> wrote:
Hello,
I could use some help making sense of the VAXstation ROM images.
A set is provided here: https://www.9track.net/roms/
The two .bin files are each one halfword of a 16-bit wide ROM for the
68000 display processor. I checked it, and it's fine.
My problem is with the Bit Blit Accelator. The board has four Am2901
bitslice processors to make up a 16-bit custom blitter. The information
I have is that the microcode is 57 bits wide and there should be 1024
words. However, this is not a great match for the rest of the ROM
images.
Some of the BBA ROMs seem to be bit masks, presumably useful for
rendering graphics. But none of them seem to match what I'd expect to
see for a 57x1024 microcode.
Here are the sizes, in bits, of the ROMs:
Bit Blit Accelerator (BBA)
23-066K3.jed 2048
23-067K3.jed 2048
23-068K3.jed 2048
23-069K3.jed 2048
23-076F4.e32 16384
23-077F4.e65 16384
23-077J5.jed 2048
23-078J5.jed 2048
23-354A1.e33 256
23-355A1.e66 256
23-356A1.e77 256
23-357A1.e85 256
Display Processor Module (DPM)
23-020L1.jed 3553
23-021L1.jed 3553
23-022L1.jed 3553
23-023L1.jed 3553
23-024L1.jed 3553
23-025L1.jed 3553
23-288E4.bin 65536 68000 code in these two.
23-289E4.bin 65536
9:30 p.m.
Paul Koning wrote:
Given 16 bit wide ROMs, I would expect the microcode
width to be
rounded up to a multiple of that, so 64 bits, which means the expected
ROM size is 64k bits. That matches two of the ROMs you mentioned.
I don't know if they are 16 bits wide. The two 68000 ROMs are 8 bit
wide. The others I have no data on.
Also, there aren't enough bits on the BBA board ROMs to make up 56x1024.
(I was wrong in my previous post, the microcode is 56 bits wide, not
57.) Besides, the contents doesn't look like code but graphics masks.
687
days inactive
688
days old
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participants (2)
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Lars Brinkhoff -
Paul Koning