Vintage Ohio Scientific Challenger 1P Superboard II Model 600 6502 BASIC SBC
Item History & Price
| Reference Number: Avaluer:51072724 | Vintage: Yes |
| Model: Intel SDK-85 | Brand: Intel |
For sale is an Ohio Scientific Superboard II (aka Model 600, aka Challenger 1P), rev D, circa 1980.
This single-board complete computer features built-in 24 line by 24 character video with NTSC composite output, Microsoft 8K BASIC in ROM, 8K of RAM (sixteen 2114 chips, of which 4K were likely added later as they are not the same brand as the first 4K). The standard installed monitor firmware allows access to machine code as well as boot to expansion floppy disk (if instal...led via an optional 610 expansion board). On-board cassette interface (load/save) was not tested. Some traces on the board are cut and some have been re-soldered: like many computers of the day, some circuitry might well have been modified for a specific use (RAM expansion on the board, video modifications to 32 columns, or even overclocking to 2MHz). These machines were very popular with the hobbyist/experimenter crowd so many C1P's from this era have modifications of some type. The circuitry on this board has been restored to the original factory design. The Monitor and four BASIC ROMs are factory masked type, the character generator is an EPROM.
The video output (NTSC composite) comes via an RCA cable which mates with a connector on the board.
All keys were tested to work (see the photo of characters produced from keypresses) and the system boots and runs fine showing all installed memory (see photos). BASIC programs typed-in run properly: in the photos you'll see a simple program that writes directly to video RAM (the display is actually 32 characters across of which only 24 are used by the system with the space at the sides used as a guard band).
Testing was performed as follows:Upon power-up (or when the reset key is pressed) the "D/C/W/M" prompt appears. Ensure the CAPS LOCK button is down and press "C" followed by ENTER several times to enter BASIC. The system shows 74xx bytes free (8K minus memory used by the system including page zero for the 6502, variables for basic, and the stack).
The keyboard was tested by pressing each key. A BASIC program was then entered via the keyboard and run. The ACIA (6850) was tested by typing SAVE then LIST at which point characters appear at the (slow) rate of about 30 per second on an external serial terminal: since the board has a built-in serial interface, the RS-232 Data Out signal on J3 (pin 2) was run to a PC running TeraTerm and characters on the screen were echoed to the terminal. Other than this simple test (which shows the ACIA is functioning and the RS-232 transmit circuitry is working), no further testing of the RS-232 input nor the cassette port were done. The connector on J3 is currently wired for cassette operation at 300 baud but it can be wired for RS-232 use allowing program upload/download via that port instead of the cassette port - a more reliable method (schematics, available on the web, show how to wire the rear connector for use as a 1200 baud printer port or a 300 baud modem port).
So, some traces have been soldered, some chips have been replaced, and the keys show some wear from use (see photos which show close-ups of the condition) but it is a decent working machine especially for its fourty-plus year age). Needs a little TLC and perhaps the odd simple repair (like cold solder joints of the keyswitches - found a few of those in which a 'flaky' key was just a bad solder joint on the bottom of the board).
Includes a coaxial cable to connect to a composite monitor. Power is supplied via two stripped wires. No other cables (e.g. for cassette) are supplied however schematics available on the web show the wiring of this cable (as well as the RS-232 port if you go that route).
Needs a 5 Volt, 3 Amp regulated power supply to run as well as an NTSC composite monitor (or perhaps an old VCR which accepts composite input but not all work with a source like this). Please check your supply with a DMM before connecting to ensure the voltage is correct and stable.
Tested as above, but due to age it is sold "as is"
Shipping is by Canada Post tracked parcel. INTERNATIONAL BIDDERS (not continental USA, e.g. Europe) please contact first as Canada Post is not shipping to all countries due to CoVid and there will likely be large delays to some countries as well. Import taxes and duties are the responsibility of the purchaser.
Combining shipping: we are happy to combine shipping. If you win more than one item please contact us BEFORE paying and we will send an invoice for the combined items.
This single-board complete computer features built-in 24 line by 24 character video with NTSC composite output, Microsoft 8K BASIC in ROM, 8K of RAM (sixteen 2114 chips, of which 4K were likely added later as they are not the same brand as the first 4K). The standard installed monitor firmware allows access to machine code as well as boot to expansion floppy disk (if instal...led via an optional 610 expansion board). On-board cassette interface (load/save) was not tested. Some traces on the board are cut and some have been re-soldered: like many computers of the day, some circuitry might well have been modified for a specific use (RAM expansion on the board, video modifications to 32 columns, or even overclocking to 2MHz). These machines were very popular with the hobbyist/experimenter crowd so many C1P's from this era have modifications of some type. The circuitry on this board has been restored to the original factory design. The Monitor and four BASIC ROMs are factory masked type, the character generator is an EPROM.
The video output (NTSC composite) comes via an RCA cable which mates with a connector on the board.
All keys were tested to work (see the photo of characters produced from keypresses) and the system boots and runs fine showing all installed memory (see photos). BASIC programs typed-in run properly: in the photos you'll see a simple program that writes directly to video RAM (the display is actually 32 characters across of which only 24 are used by the system with the space at the sides used as a guard band).
Testing was performed as follows:Upon power-up (or when the reset key is pressed) the "D/C/W/M" prompt appears. Ensure the CAPS LOCK button is down and press "C" followed by ENTER several times to enter BASIC. The system shows 74xx bytes free (8K minus memory used by the system including page zero for the 6502, variables for basic, and the stack).
The keyboard was tested by pressing each key. A BASIC program was then entered via the keyboard and run. The ACIA (6850) was tested by typing SAVE then LIST at which point characters appear at the (slow) rate of about 30 per second on an external serial terminal: since the board has a built-in serial interface, the RS-232 Data Out signal on J3 (pin 2) was run to a PC running TeraTerm and characters on the screen were echoed to the terminal. Other than this simple test (which shows the ACIA is functioning and the RS-232 transmit circuitry is working), no further testing of the RS-232 input nor the cassette port were done. The connector on J3 is currently wired for cassette operation at 300 baud but it can be wired for RS-232 use allowing program upload/download via that port instead of the cassette port - a more reliable method (schematics, available on the web, show how to wire the rear connector for use as a 1200 baud printer port or a 300 baud modem port).
So, some traces have been soldered, some chips have been replaced, and the keys show some wear from use (see photos which show close-ups of the condition) but it is a decent working machine especially for its fourty-plus year age). Needs a little TLC and perhaps the odd simple repair (like cold solder joints of the keyswitches - found a few of those in which a 'flaky' key was just a bad solder joint on the bottom of the board).
Includes a coaxial cable to connect to a composite monitor. Power is supplied via two stripped wires. No other cables (e.g. for cassette) are supplied however schematics available on the web show the wiring of this cable (as well as the RS-232 port if you go that route).
Needs a 5 Volt, 3 Amp regulated power supply to run as well as an NTSC composite monitor (or perhaps an old VCR which accepts composite input but not all work with a source like this). Please check your supply with a DMM before connecting to ensure the voltage is correct and stable.
Tested as above, but due to age it is sold "as is"
Shipping is by Canada Post tracked parcel. INTERNATIONAL BIDDERS (not continental USA, e.g. Europe) please contact first as Canada Post is not shipping to all countries due to CoVid and there will likely be large delays to some countries as well. Import taxes and duties are the responsibility of the purchaser.
Combining shipping: we are happy to combine shipping. If you win more than one item please contact us BEFORE paying and we will send an invoice for the combined items.
