This is an old post, preserved for reference.
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Went working on old computers, there is always a problem with getting hold of replacement ICs. Some are easier than others, WDC are manufacturing modern versions of the 6502, 6520/21 and 6522, and there are still supplies of various types of RAM. One of the more difficult to replace is the 6530.
- 2 6502 CPUs
- 4 sets of RAM - a bank of 2114s (4K), 2 x RIOT (128 bytes each) and a RRIOT 64 bytes)
- 4 sets of ROM - 3 mask ROMs (2x4K, 1x2K), one RRIOT(1K)
- 4 I/O chips - a 6522, a RRIOT and two RIOTs
So quite a lot on there to go wrong. In the later Commodore disk drives (the 8250LP , 8296D and SFD-1001), it looks like they had been designed to use a 6530, but they all seem to be fitted with adapter boards. These had a 6530 from another drive, and some logic so the ROM on there wasn't enabled, and a separate ROM chip which had the right code in. This was presumably a way of using up the stock of old 6530 chips. I don't have a stock pile of old 6530 chips. But I do have 6532 RIOTs. The 6532 is very similar to the 6530 but without the ROM, so RIOT is RAM, I/O and Timer. This chip is not programmable, so more easy to find. There is one in every Atari 2600, I actually use a 2600 to test 6532's.
6530 replacement, this my interpretation, along similar lines.
zimmers.net, including the one in the adapter board on the 8250LP. With those ROM images, this board will replace the following 6530s:
- 901466-04 (6530-34) - Shugart SA390 drives in 4040, DOS 2.2
- 901483-03 (6530-28) - Micropolis 1006 drives in 8050, DOS 2.5
- 901885-04 (6530-47) - Micropolis 1006 drives in 8050/8250, DOS 2.7
- 901869-01 (6530-48) - MPI 101/102 drives in 8050/8250 DOS 2.7
- 251474-01B - Matsushita JU-570-2 drives in 8250LP, DOS 2.7
using openCBM to write disk images, and the wonderfully literal BASIC 4 'copy an entire disk' command, COPY D0 TO D1.