Sothius' Home

-

Museum

-

Commodore

-

Commodore 64C

-

additional pictures

Commodore 64C
Additional pictures. Note that loading the page could take a while...
(pictures copyright by M.A.Grundke)

serial number: HB4 1428155E

Overview of the ASSY 250469-board: This late board is highly integrated, thus occupying only half of the space compared to the older boards. There's not much TTL left, since it's all been integrated somewhere. Furthermore, most ICs have changed their locations: Leftmost there's one of the two CIAs (U2, covered by a shadow on this pic). Right from it, the two ROMs (U5,U4). Note that the ROM at U4 now contains CBM BASIC and CBM KERNAL (which were two seperate ROMs in all older boards). Again right, you can see the CPU (U6) with the two small RAM chips (U10,U11) below. Heading right again, there are the MMU ('64 pin monster' at U8, didn't exist in earlier boards and now contains, among other things, the PLA), the color SRAM (U19), VIC-II (U7) and MOS 8701 (U20). Note that VIC and clock generator are not shielded anymore! Further right are SID (U9), the other CIA (U1) and the keyboard connector (CN1). As you can see, this board is a masterpiece of cost-reduction!

board silkscreening: PCB ASSY NO. 250469 PCB NO. 252311 REV.A As you can see this is exactly the same board-revision like that of my C64G (called 'C64 version BN/E'). But this is true only for the latest C64C, that were produced simultaneously to the C64G

CSG 8500 is simply a HMOS-2-produced MOS 6510. The whole 85xx-chipset was not only built for cost-reduction but also to solve some problems with onboard-voltage, that some of the older machines had. Also note that MOS Technologies had been renamed to Commodore Semiconductor Group (GSG) these days

All later C64-boards have a MMU (memory managament unit), that contains the former PLA ('programmable logic array') and replace very much TTL used on the older boards. In latest revisions (ASSY 250469 REV.B and higher) it even contains the color RAM, reducing production cost even more. Note that this MMU was produced by SHARP under partno. LH5062B. Below it, their customer's (MOS Technology) partno., 251715-01

This later C64-board design makes use of only two 64Kx4 RAMs (in this case SHARP LH2464-12) for cost reduction. Boards prior to ASSY 250466 had 8 pcs. 64Kx1

CSG 8565 is a 'standard' VIC-II that was made with CBM's HMOS-2 process, fitting rest of the 'new chipset' and running at 5V now (the older version needed 12V, and passive cooling...). Above it, the MOS 8701 clock generator, which is used in board revisions since 250425 to replace some TTL ICs. Below it, finally, a SANYO LC3514A-15 SRAM (1Kx4), providing 512 Bytes for the use as color RAM

And again, CSG 8580 doesn't differ much from its ancestor, the MOS 6581; it was just adopted to work with the 'new 85xx chipset'. One of these changes includes lowering its input voltage to 9V, instead of 12V in the older machines

One of the two CSG 6526A, which was used for I/O in all C64s. However, this A-version of the MOS 6526 could be clocked up to 2 MHz, but the C64/ C128s I/O is fixed at 1 MHz. Behind it, a Motorola MC14066BCP quad analog switch and the keyboard connector

The C64C's ROMs: C251913-01 (contains the 901226-01 BASIC and 901227-03 KERNAL ROMs) and C901225-01 character generator ROM. Below them, the machine's second CIA

Also have a look at the C64G (ASSY 250469) page
(same board revision but with a slightly different upmost layer)

Sothius' Home

-

Museum

-

Commodore

-

Commodore 64C

-

additional pictures