Version 1.21, July 14, 1999
This is the current version of the Handy Board, publicly released in July, 1999.
Changes in this version:
- The E clock signal is now available on the Expansion Bus, immediately to the right of the MEM PWR line. J3 is now a 11-pin header (instead of 10 pins).
- Additional mounting pads were added for VR1, the user thumbwheel, to support a nice thumbwheel now available from Digikey (part number P4D2203-ND).
Version 1.2, November 1995
This version of the Handy Board was publicly released in November, 1995.
This version corrects an error in the address decoding that rendered half of the Expansion Bus unusable. The error snuck into version 1.1 and was preserved in version 1.11. (If you have one of these earlier boards, see instructions for fixing the addressing.)
The summary of changes:
- Bigger mounting holes for the 1N4001 diode and battery wires.
- Pad spacing for the two pushbutton switches was fixed.
- A fourth hole was added to the analog expansion connector.
- As indicated, the expansion addressing was fixed. Expansion latches are now mapped into the address ranges 0×4000 to 0×4fff (bank 0), 0×5000 to 0×5fff (bank 1), 0×6000 to 0×6fff (bank 2), and 0×7000 to 0×7fff (bank 3, the on-board digital inputs and motor outputs).
Version 1.11, July 1995
This extremely minor revision fixes a single bug discovered on the 1.1 board (thanks to Robert McCartney for first discovering and reporting the bug).
- The ‘hc138 chip was not grounded; this was fixed.
No other changes were made; the version 1.1 schematics and parts list apply to the version 1.11 board.
This version is being tested at MIT.
- A needed pull-up resistor was added to the STOP switch circuit.
- The switch PCB pads were given more space for ease of mounting.
- The memory and peripheral address decoding was changed to get rid of resistors in the logic path.
- The signals AS, A15, and MEM-PWR were added to expansion bus. This will facilitate memory on an expansion board. This is the only “new feature” of the version 1.1 board per se.
- The board was made 0.1 inches longer in length and width. This allows it to sit on top of the specified plastic enclosure, providing more room for component tails underneath the board (between the board and the battery).
- Information was added to the silkscreen: sensors were numbered and the board revision level was marked.
This is the first board released. A group of about 15 beta testers received the boards.
- An error in the wiring of the ‘hc373 chip was fixed (wires to pins 1 and 11 were swapped).
- An RJ11 jack for the SPI circuit was removed. In its place is now a 8-pin header for the SPI signals, and a DC power jack with battery charging circuit (so the board can charge its own battery simply by plugging in an adapter).
Version 0.9, April 1995
This was the first board run. Two copies were made for initial debugging.