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Sothius' Home-Museum- AMIGA-Amiga 500-additional pictures

Amiga 500
Additional pictures. Note that loading the page could take a while...
(pictures copyright by M.A.Grundke)

A500 REV.6A serial number (16 KBytes)
C= COMMODORE
MODEL A500
SERIAL NO. 709506


A500 REV.6A board-overview (65 KBytes)
A500 REV.6A board-overview (with internal disk-drive to the right):
Beginning from the left, you can see the large male edge connector (external expansion-slot), with the large DIP-IC (CPU, U1) to its right. Above CPU, there's Denise (U4) with video output circuits. Right from Denise, the first ('ODD','A') CIA at U7, and Paula (U3) below. Still below are Fat Agnus (U2, PLCC-case) with the Kickstart-ROM (U6, next to CPU) left from it. Below Agnus, the Kick-ROM and a large silk-screening ('C=A500') are the machine's 512KB RAM (4 pcs. 256Kx4), and, further right, the internal expansion slot. Up from there and right from Paula is Gary (U5), with the two tiny RS232 converters (Motorola 1488 & Motorola 1489P, left at U38 & U39) and the second ('EVEN','B') CIA (U8) above. Still above the EVEN CIA are the interal disk-drive connector (CN11) and the floppy's power connector (CN12). The whole board is normally covered by a PCB shielding


A500 REV.6A board-info part 1 (31 KBytes)
board silkscreening, part 1:
C=A500
Below you can partly see the 512 KByte RAM and the empty sockets for additional 512 KBytes, which were never filled by default


A500 REV.6A board-info part 2 (13 KBytes)
board silkscreening, part 2:
ARTWORK NO
312513 REV 6A
ASSY 312510
© COPYRIGHT -
COMMODORE 1988


A500 REV.6A board-info part 3 (20 KBytes)
board silkscreening, part 3 (mostly covered by a sticker):
B52/ ROCK LOBSTER
GRR/JSP/GUAY/FISH
RVW/VFA/DCA
HJM/CJW/TC/SMK
GET/LLK/ITOH/BCN
C=A500 REV 6A
Sticker:
A 500 P
HKC S/N 1002831
WW /89/90


A500 REV.6A board-info part 4 (21 KBytes)
board silkscreening, part 4:
FAB 312512


A500 REV.6A CPU (32 KBytes)
The well-known 68000, the A500's CPU. This one's OEM-manufactured by Signetics (a company that doesn't exist anymore - today, it's part of Philips Semiconductors)


A500 REV.6A Agnus (29 KBytes)
The MOS 8372A can handle up to 1 MByte ChipRAM and can be used either in PAL- or NTSC-machines. All A500 since Revision 6 got the 8372A - machines prior to that revision used the 8370 (NTSC) or 8371 (PAL), which could only handle 512 KBytes ChipRAM. PAL or NTSC-modes can either be selected by setting a jumper, or by switching the 8372A by software. That's very useful for cost-reduction, since you don't have to produce different machines for PAL- and NTSC-countries


A500 REV.6A RAM bank (49 KBytes)
The machine's RAM bank (4 pcs. Texas Instruments TMS44C256-12N, 256Kx4-organized). Note that the board can also be outfitted with 1 MB RAM (as indicated by the board's silk-screening). However, this was never done in A500-production, but the later A500 Plus (with nearly the same board-design) used all the sockets for its default 1 MB ChipRAM. You could, by the way, use this sockets to expand the machine on your own. But then the internal expansion slot wasn't usable with memory expansions anymore, because the address-lines utilized are the same


A500 REV.6A Kickstart-ROM (30 KBytes)
C315039-02 is the Kickstart 1.3-ROM used in this A500. The Kickstart 1.2 (C315093-01), which came with pre-Revision 6 machines (i.e. before 1988) had no Autoboot-capability and was thus replaced quickly when the many Amiga harddisk-solutions (like the A590) came up (who wants to boot AmigaDOS with a startup-diskette?). Additionally, Kick 1.3 supported the new Fast File System (FFS), speeding up DMA-access and increasing available diskspace (up to 4.9% according to the manual)


A500 REV.6A keyboard-controller (21 KBytes)
The Amiga-series' keyboard-controller, the CBM 6570. In the later AA-machines, it was integrated in a gate array ('keyboard MPU') on the main board


A500 REV.6A Denise (25 KBytes)
MOS 8362 'Denise', the OCS' graphics chip. This Revision 8 Denise appeared in the A500 first. The A1000 had 8362R6 or earlier revisions - some of these couldn't display the EHB (extra half-brite) mode with 64 colors


A500 REV.6A Paula (23 KBytes)
MOS 8364 'Paula' , the OCS's soundchip and holding some registers needed for floppy-access. When it appeared in the A1000, its capabilities were enough by far. But in all the years of Amiga-development, it's never been changed - only some prototypes (like the A3000+) had a DSP, which never made it into the finally released machines, due to the cost


A500 REV.6A CIA (23 KBytes)
One of the two MOS 8520 'CIA'. They were used for all Amigas' I/O (although sometimes being part of a gate array or in PLCC-format) and were basically 8 bit MOS 6522, modified for use in the Amiga-design


A500 REV.6A Gary (23 KBytes)
MOS 5719, 'Gary', is present in all OCS/ ECS-machines (except for the A600, in which it's part of the Gayle-customchip). It controls the floppy-motor (stepping) and is used for logic functions. In the AA-machines, it is also integrated in 391424-02 Gayle (the A600's heritage)


A500 REV.6A RS232 (31 KBytes)
These two ICs, Motorola MC1488 (driver) & MC1489P (receiver) do the RS232-conversion, meaning that they convert logic level voltages (0V, 5V) to RS232-level (i.e. +3V, representing a binary zero and -3V for a binary one)



Also see the Amiga 500 Plus' board design!


Sothius' Home-Museum- AMIGA-Amiga 500-additional pictures