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Sothius' Home-Museum- ATARI-ATARI 2600 jr. (REV.C)-additional pictures

ATARI 2600 jr.
(REV.C)
Additional pictures. Note that loading the page could take a while...
(pictures copyright by M.A.Grundke)

ATARI 2600 jr. REV.C serial plate (22 KBytes)
ATARI 2600 jr. REV.C serial plate:
MANUFACTURED FOR ATARI,CORP.BY ATARI
TAIWAN MANUFACTURING CORP. IN TAIWAN
MODEL NO. CX2600 JR.
S.N. AT860288470


ATARI 2600 jr. REV.C board overview (64 KBytes)
ATARI 2600 jr. REV.C board overview:
let's first have a look at connectors & switches on the machine's back. From left to right there are CHANNEL 2/3 switch, left controller port, left controller difficulty setting, DC-in, right controller difficulty, right controller port and RF-output. Moving down from the RF-out, is a fixed-mounted foil-cable for SELECT and RESET-buttons on top of the machine. Still below, normally covered by its own PCB shield, the RF-circuitry with two hex inverters (CA3086, DIP14 at A5 and CD4050BE, DIP16 at A4). Right from location A4, in the front-right corner of the board, by the way, an adjustment screw. Clearly dominating the board is the cartridge slot in the middle, with the three customchips below: UM6532 (A1), UM6507 (A2) and UM6526P1 (A3). Left from the cart slot, finally, the two switches for COLOR/ BW and POWER ON/OFF can be found directly soldered to the board, surrounded by resistors, capacitors and the power LED (below). Note that the whole board is normally shielded. By the way, all PAL-VCS are clocked by two crystals, instead of one in the NTSC-machines (see board's lower left - the outlined area with the second crystal is not populated in NTSC machines). The reason is that besides the color circuitry's crystal (at Y1), the PAL-machines need an additional one (at Y2) to create the PAL color-carrier frequency


ATARI 2600 jr. REV.C board info 1 (18 KBytes)
board silkscreening, part 1:
ATARI ®
© 1983


ATARI 2600 jr. REV.C board info 2 (20 KBytes)
board silkscreening, part 2:
CAO
REV
(both fields left blank)


ATARI 2600 jr. REV.C board info 3 (24 KBytes)
board silkscreening, part 3:
ATARI C021503 REV C
(lower side of the board)


ATARI 2600 jr. REV.C board info 4 (10 KBytes)
board silkscreening, part 4:
G-AV-O
2786
(lower side of the board; '2786' could be the production-date: week 27 year 1986)


ATARI 2600 jr. REV.C CPU (34 KBytes)
The 2600 jr.'s CPU, an UMC UM6507. It's a 28-pin MOS 6502 with only 13 external address-lines (A0-A12 - the 6502 has 16, A0-A15) but without interrupt inputs (except for the RDY-signal). Because of its address-lines, it's only able to address 8 KBytes RAM directly


ATARI 2600 jr. REV.C TIA (36 KBytes)
UM6526P1 'TIA' ('Television Interface Adaptor') includes 6 registers used as A/D-converters. Technically, its function is similar to the later CTIA/ GTIAs of the XL/XE-series. The difference is, of course, that there's no ANTIC to control it! In the VCS 2600-design, the CPU has to do that itself... Interesting is (as mentioned earlier), that UM6526 is both PAL- and NTSC-version - the only difference between the machines is the additional crystal for creating the PAL color-carrier frequency. Thanks to Karl Roussel, in that context, for sending me mainboard pics of his NTSC VCS jr.


ATARI 2600 jr. REV.C 6532 (39 KBytes)
The UMC UM6532 ('RIOT' or 'PIA', 'Peripheral Interface Adaptor') is a standard-IC and responsible for the 2600's I/O. It contains two 8 bit bi-directional I/O-ports, a interval timer plus timer IRQ and the 2600's 128 Bytes SRAM ('SARA'). In comparison to its ancestor, the 6530 RIOT (used in the Commodore CHESSmate, for example), it does not contain a ROM-section


ATARI 2600 jr. REV.C cartridge slot (42 KBytes)
The 2600 jr.'s 24-pin cartridge slot, which can take cartridges with up to 32 KBytes, although bankswitching is needed for these. That's because the machine's 'external address range' is only 4 KBytes (although the 6507 could address 8 KBytes directly, 4 KBytes in the 2600's memory map are reserved for internal addresses)



Also see the ATARI 2600 jr. REV.F1, with its newer board!


Sothius' Home-Museum- ATARI-ATARI 2600 jr. (REV.C)-additional pictures