Deramp Altair 8800c Manual Download Page 11

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Page 11

Interface Board Assembly

Assembly of the interface board is fairly straight forward, however, these instructions won’t teach you
how to solder components on a PCB, solder connectors, or show you the difference between a resistor
and a diode. If you have any concerns about building this board, please contact me first.

Parts List (interface board)

Designator Description

Part Number

Distributor

10uf, 25v tantalum

80-T350E106K025AT

Mouser

C2-C17

0.1uf, 50v

2146302

Jameco

D1*

1N5817 Schottky Diode

511-1N5817

Mouser

50 pin, dual row IDC right-angle header

517-D3433-5302-AR (3M)

Mouser

50 pin IDC socket (x2)

MKC50A-ND

DigiKey

50 pin IDC strain relief (x2)

MKSR50-ND

DigiKey

50 conductor ribbon cable

MC50G-1-ND

DigiKey

8 pin, right-angle Molex header

538-26-60-3080

Mouser

Female Housing (x2)

09-50-7081

Mouser

Crimp Pins (x16)

08-50-0106

Mouser

J3*

Not stuffed

IC-A

PIC16F1828 Processor

579-PIC16F1828IP

Provided

IC-B

74LS30 Single 8-Input NAND

595-SN74LS30N

Mouser

IC-C

74LS164 Parallel Out Shift Register

595-SN74LS164N

Mouser

IC-D,I

74LS374 Octal Latch

595-SN74LS374N

Mouser

IC-E,F

74LS109 Dual J-K* Flip Flop

595-SN74LS109AN

Mouser

IC-G,L

74LS02 Quad 2-Input NOR

595-SN74LS02N

Mouser

IC-H

74LS00 Quad 2-Input NAND

595-SN74LS00N

Mouser

IC-M

74LS04 Hex Inverter

595-SN74LS04N

Mouser

IC-J

74LS244 Octal Bus Driver

595-SN74LS244N

Mouser

IC-K

74LS10 Triple 3-Input NAND

595-SN74LS10N

Mouser

IC-N

74LS368 Hex Inverting Bus Driver

595-SN74LS368AN

Mouser

R1,R2,R4,R6

4.3K, 1/4w, 5%

291-4.3K-RC

Mouser

R3,R5

1K, 1/4w, 5%

291-1K-RC

Mouser

T1-T3

2N4401 Transistor

610-2N4401

Mouser

VR1

7805 Regulator

511-L7805ACV

Mouser

Heatsink

129242

Jameco

4/40 x 3/8" screw

#4 internal tooth lockwasher

4/40 nut

* J3 is not stuffed and a jumper wire can be substituted for D1 if this board will never be attached to a Microchip

PIC programmer. Since firmware updates can be applied without using a programmer, these parts are most like-
ly not needed.

Part Notes

Use only LS-TTL parts

. Some IC inputs are tied directly to Vcc. Multi-emitter TTL inputs do not tolerate

this well (e.g., 74xxx and 74Sxxx).

Summary of Contents for Altair 8800c

Page 1: ...ed and like the original front panel board finding an original cabinet by itself is nearly impossible As an alternative the cab inet for the Altair 8800 Clone is still available however the original f...

Page 2: ...us should drive the PRDY signal with an open collector driver The signal is terminated on the CPU board with a 1K pull up resistor However the original front panel board actively drives this signal hi...

Page 3: ...APEM 5236AB Search for best deal S10 S25 Toggle Switch On None On Gold APEM 5236CDB Search for best deal S2 S9 Toggle Switch On Off On Gold APEM 5237CDB Search for best deal Switches If at all possibl...

Page 4: ...the PCB looks a bit different than the 8800c front panel board Ignore the LED orientation polarity shown in the pictures 1 Prop the front panel bracket an inch or two above your work surface and orien...

Page 5: ...rd level and square on the switches The next step is to install the front panel LEDs In order to hold the LEDs at the proper and consistent height above the board use the front dress panel as a jig Do...

Page 6: ...fy that the front panel and PCB look perfectly parallel to each other and are resting directly on all of the white spacers See the pictures on the next page 6 Solder the LEDs Press down gently on the...

Page 7: ...eying slot before soldering the connector onto the board Again the connector goes on the back side of the board J2 Though not a requirement I d recommend pulling the center pin out of the J2 connector...

Page 8: ...anel firmly around a few of the switches to free those spots where the support bracket may be caught on the switch threads 2 Install a lock washer and nut finger tighten only on the power switch all e...

Page 9: ...nd wiched the spacers 3 Work the front panel down around the switch bushings as needed until the front panel is flat and even over all 25 switches When properly assembled the bushings generally protru...

Page 10: ...des approximately equal as you work the panel backwards into place where the mounting bracket s threaded holes line up with the four holes in the bottom of the case 2 Attach the front panel support br...

Page 11: ...Input NAND 595 SN74LS30N Mouser IC C 74LS164 Parallel Out Shift Register 595 SN74LS164N Mouser IC D I 74LS374 Octal Latch 595 SN74LS374N Mouser IC E F 74LS109 Dual J K Flip Flop 595 SN74LS109AN Mouser...

Page 12: ...required J1 Cable Assembly A 50 pin ribbon cable connects the front panel board to the interface board in the bus One way to route this cable is shown in the picture below Here the cable exits towards...

Page 13: ...th plated mounting holes that are connected to DC ground may make this connection to chassis ground for you as well If putting screws through pre drilled holes in the cabinet paint may prevent electri...

Page 14: ...MSB of Power On Jump Address zero disables VDIP 3 MSB of Reset Jump Address zero disables Power On Reset By default and to behave like the original Altair 8800 front panel the run state of the 8800c...

Page 15: ...ippet on switches A7 A0 see below and then depressing AUX Left After injection an examine of the start address is automatically performed so simply depressing run starts the loaded code The code injec...

Page 16: ...lls so the lower num ber wins See http deramp com downloads altair software miscellaneous Intel Hex Loader Loads an Intel hex file through the chosen 2SIO serial port The program is relocatable Set sw...

Page 17: ...pecified address if the computer is running Note that if the computer is not running when RESET is actuated or a STOP RESET is performed this has the effect of examining the auto jump address upon res...

Page 18: ...uld appear on the terminal emulator window Follow the prompt to send the hex file that contains the firmware update from the PC Once the hex file is received the update is automatically programmed int...

Page 19: ......

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Page 24: ...Pulse high to latch shift register parallel outputs into the CPU inject latch B5 12 smUNPROT Low to assert bus UNPROT signal memory unprotect B4 13 smSEROUT Serial data output to shift register to up...

Page 25: ...7 SERIN 8 N C 9 N C 10 WAIT 11 HLDA 12 A15 13 A14 14 A13 15 A12 16 A11 17 A10 18 A9 19 A8 20 A7 21 A6 22 A5 23 A4 24 A3 25 A2 26 A1 27 A0 28 N C 29 Gnd 30 Gnd 31 Gnd 32 Gnd 33 INTE 34 PROT 35 MEMR 36...

Page 26: ...AND 1 1 K 1 3 of K used 74LS30 Single 8 Input NAND 1 1 B 74LS04 Hex Inverter 5 1 M 5 6 of M used 74LS368 Hex Bus Driver 6 1 N 74LS109 Dual J K Flip Flop 4 2 E F 74LS374 Octal Latch 2 2 D I 74LS244 Oct...

Page 27: ...72 pRDY RDY signal OR d with others to 8080 23 DODSB Data Out bus disable DO7 DO0 73 pINT Interrupt request to 8080 24 PHI2 Phase 2 clock 74 pHOLD Hold request to 8080 25 PHI1 Phase 1 clock 75 pRESET...

Page 28: ...the case 4 Remove the front dress panel from the unpainted support bracket by removing the six nuts from the back side of the support bracket Remove and save all hardware including the six white spac...

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