| Name | ATARI 2600 Video Computer System (also known as '2600 jr.') |
| Codename | - 'Bonnie'
- in the ATARI 2600 Development Kit, the machine was called 'ATARI MICROPROCESSOR GAME SYSTEM'
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| Made by | - ATARI Corp.
Sunnyvale, California - this one was produced in Taiwan (see serial number)
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| Released | - 1986 (although developed in 1983, see misc)
- the first VCS 2600 (model CX-2600) was introduced in June 1977 (on Summer-CES)
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| Serial-No. | S.N. AT860288470 |
| Additional Info | MANUFACTURED FOR ATARI,CORP.BY ATARI
TAIWAN MANUFACTURING CORP. IN TAIWAN
MODEL NO. CX2600 JR. |
| Board-info | |
| CPU | UMC UM6507- the 6507 basically is a 6502 with only 13 address-lines, thus stripped down to an 8 KB address range. It also has fewer interrupt-inputs (i.e. it lacks IRQ- and NMI-lines)
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| Speed | 1.182298 MHz (PAL)/ 1.193 MHz (NTSC)- PAL- and NTSC-machines seem to be clocked different. While NTSC-VCS have only one 3.58 MHz oscillator at location Y1, the PAL-VCS have two: one clocked with 3.5468 MHz (used for color burst at Y1), a second with 4.433618 MHz (used for PAL color-encoding carrier frequency at Y2). Since NTSC-VCS create their CPU-clock by dividing 3.58 MHz by 3, I assume that shouldn't be different for PAL-machines (3.546894 MHz/ 3 = 1.182298 MHz)
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| RAM | 128 Bytes (128x8 SRAM), integrated in UM6532- was also called 'SARA' (e.g. in the Development Kit)
- this RAM can only be used for storing data, not program code
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| ROM/ Native OS | - cartridges with 2 to 32 KBytes capacity
- bankswitching was needed for carts greater than 4 KBytes, because the address space for 'external memory' is only 4KB in the 2600-design (and of course because of the cartridge slot's lack of more address lines)
- ATARI had created 'game standards', which came with the documentation of the development kits. These standards included the look of the games, or how they should utilize the machine's buttons. But what's far more interesting, it also included PAL/ NTSC/ SECAM-compatibilty! Having a look at the 2600-games today, it seems only few developers obeyed these rules, since most games will not work with different TV-standards...
Also interesting: that passage mentioned ('Foreign Versions') was omitted in the later 7800 game standards. Probably ATARI had given up on that?
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| Keyboard/ Layout | - none, but there was the ATARI 'Graduate'-prototype (never sold) which was a keyboard with its own CPU, OS and enhanced graphics
- has 3 switches on its back: one to switch between Channel 2 and 3 and two to set difficulty level for each port. Also has a button to switch between B&W and color-TV, as well as SELECT- and RESET-buttons (all three on its top)
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| Graphics | UMC UM6526P1 TIA ('Television Interface Adaptor')- Maximum resolution:
- there are no 'display modes'; TIA just outputs 'frames' with a maximum of 228 clock counts and 312 vertical lines (PAL)/ 262 lines (NTSC)
- the effective resolution is 160x228 (PAL)/ 160x192 (NTSC), because the frame contains 68 horizontal blank clock counts (HBLANK), 3 vertical sync lines (VSYNC), 45/ 37 vertical blank lines (PAL/NTSC VBLANK) and 36/30 overscan lines (PAL/NTSC)
- Maximum colors: 16 from a 128 color palette (16 hues * 8 luminances)
- TIA can generate 'playfields' (i.e. background) with a
maximum of 5 movable objects (i.e. sprites), and provides collision detection
- this machine's a PAL version. For appropriate timing of TV-output (depending on the TV-standard), NTSC-VCS use the 3.58 MHz oscillator at Y1, which also generates the CPU-clock. In PAL-machines, two oscillators are used: a 3.5468 MHz at Y1 (color-burst signal) and a 4.433618 MHz at Y2 (PAL color-carrier frequency). The UM6526P1 seems to be PAL- and NTSC-capable, as Karl Roussel reported (he's got an NTSC-machine with it, of course missing the PAL oscillator circuitry)
- TIA is direct predecessor to the ATARI 7800's MARIA, and the ancestor of CTIA and GTIA used in the XL/XE-series.
It was later called 'Stella', which is also the earlier VCS' codename
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| Sound | generated by TIA- TIA contains two independant audio-circuits. Each can be programmed
- in volume (16 levels possible)
- to output sound at a given frequency (1-30 KHz) or
- to output various noises (noise-tone generator)
However, although both circuits can be used simultaneously, they only output to one speaker (i.e. mono) - in PAL-machines, sounds are generated with a lower pitch. That's because the crystal oscillator at Y1 (which clocks TIA) is slower (see 'Graphics')
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| Media | cartridges via 24 pin slot on its top (see 'ROM') |
| Input/ Output | UMC UM6532 RIOT/ PIA (interval timer/ timer IRQ, two 8 bit I/O-ports)
UMC UM6526P1 TIA (again) to trigger the joystick-buttons |
| Miscellaneous | - The 2600 jr. was the last of the successful VCS 2600-series
- It was originally designed in 1983 as ATARI CX-2000 'Val'-system with built-in joysticks. The project was cancelled because these joysticks were unpractical - they were removed and in 1986 the 2600 jr. was born, a console for the low-cost markets
- The 2600 jr. was made until 1991, and the very first VCS 2600 (model CX-2600) appeared in 1977 - no wonder the 2600-series was the best-selling video game ever!
- In comparison with its ancestor, the 2600 jr. is smaller and not that heavy, due to cost-reduction (the CX-2600 had much thicker shielding)
- After having released the ATARI 7800 in 1986, ATARI decided to relaunch the VCS 2600 on the japanese market. The new machine was called ATARI 2800, and used a '7800-style case' with 2600-technology
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