Data I/O Sprint S421x adapter for MCS-48 microcontrollers
8741AH , 8742AH , 87C42 , 8748H , 87L42 , 8748 , 8744H
here is the Eagle 5.12 board file (use any evaluation version 5.x or later to open)
* Q1: 3.58 MHz; C1, C2: 33pF. Instead of the NTSC crystal any frequency between
3 and 4 MHz should work. The capacitor values are not critical.
* D1: BAT46 or AA118 or some other schottky type. Provides Vdd to pin 26 when Vpp is off.
* D2: 1N4148. Provides high to pin 7 (EA).
* R1, R2: 1kOhm. Sets pin 6 high and pin 9 low.
* R3, R4: 22kOhm; D3, D4: 3.3V zener, e.g. BZX55C3V3. Reduces Vpp for EA (pin 7) and PROG (pin 25).
J1+J3 to be closed for single Vpp controllers (i87C42). This shorts out the
zener, so D2, D3 and R4 are not needed for these devices.
J2+J4 to be closed for 25/23V and 21/18V dual voltage controllers. Sprint software will tell you which jumpers are required.
J2 means the 1st and 2nd, J3 means the 3rd and 4th, and J4 the 4th and 5th pin in the 5 pin group, always counted from the top.
As usual, the adapter has to be placed in the socket like a 24pin chip, i.e. using the lower 24 contacts. I have tested it with TOP-40 and TOP-48 and C/99 software. With C/96 some algorithms failed, maybe they have been fixed in the later version.
SMS Sprint Expert Resources page
26 décembre, 2014