Texas Instruments Home Computer 99/4A
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- For more information, see this article's corresponding Wikipedia page: TI-99/4A.
TI-99/4A
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| Preliminary Information | |
|---|---|
| Release Year | 1981 |
| Leak Risk | Not Sure |
| Batteries | None |
| Mounting Technology | Through Hole, Sockets |
| Capacitor Types | Aluminum Electrolytic |
| Destructive Entry | No |
Original Parts
Power Supply
4A/PS
NO
1049689-2
| RefDes | Qty | Capacitance | Voltage | Mount | Diameter/Size | Height | Lead Spacing | Temp | Type | Brand | Series |
|---|---|---|---|---|---|---|---|---|---|---|---|
| C7, C10 | 2 | 47 µF | 16 v | THT | 6mm | 12mm | Axial | 85 °C | Electrolytic | Nichicon | SE(M) |
| C8 | 1 | 1000 µF | 25 v | THT | 13mm | 26mm | Axial | 85 °C | Electrolytic | Nichicon | SE(M) |
| C9 | 1 | 3300 µF | 35 v | THT | 22mm | 39mm | Axial | 85 °C | Electrolytic | Nichicon | (M) |
| C12 | 1 | 4.7 µF | 50 v | THT | 6mm | 12mm | Axial | 85 °C | Electrolytic | Nichicon | SE(M) |
| C15 | 1 | 470 µF | 12 v | THT | 12.5mm | 24mm | 5mm | 105 °C | Electrolytic | Nippon Chemi-Con | CERX |
Main Board
The main board of the TI-99/4A has very little silkscreening. The only permanent marking on the board are an unrecognizable symbol followed by "-24 (ET) 246".
| RefDes | Qty | Capacitance | Voltage | Mount | Diameter/Size | Height | Lead Spacing | Temp | Type | Brand | Series |
|---|---|---|---|---|---|---|---|---|---|---|---|
| C1, C2, C7 | 3 | 100 µF | 16 v | THT | 8mm | 16mm | Axial | 85 °C | Electrolytic | Nichicon | SE(M) |
| C3 | 1 | 10 µF | 16 v | THT | 5mm | 12mm | Axial | 85 °C | Electrolytic | Nichicon | SE(M) |
| C4, C5, C6, C8, C9 | 5 | 22 µF | 16 v | THT | 6mm | 12mm | Axial | 85 °C | Electrolytic | Nichicon | SE(M) |
The reference designations used for the main board here are not official as there are no designations silkscreened onto the PCB. See the image of the main board for the designations.
| RefDes | Qty | Part Number/Model Number | Manufacturer (If Applicable) | Explanation | Datasheet |
|---|---|---|---|---|---|
| Unknown/None | 8 | MK4116N-2GP | MOSTEK | 16,384*1-Bit DRAM | MK4116 |
| Unknown/None | 1 | SN74LS224N | Texas Instruments | Octal Buffer and Line Driver | SNx4LS24x |
| Unknown/None | 1 | CD2155ANL | Texas Instruments | ||
| Unknown/None | 1 | CD2156NL | Texas Instruments | ||
| Unknown/None | 1 | CD2157NL | Texas Instruments | ||
| Unknown/None | 1 | SN94624N | Texas Instruments | ||
| Unknown/None | 1 | RC4558P | Texas Instruments | Op Amp | RC4558 |
| Unknown/None | 1 | SN74LS156N | Texas Instruments | Decoder/Multiplexer | SN74LS156 |
| Unknown/None | 3 | SN74LS04N | Texas Instruments | Hex Inverter | SN74LS04 |
| Unknown/None | 2 | SN74LS00N | Texas Instruments | Quad 2-Input Positive-NAND Gates | SNx4LS00 |
| Unknown/None | 1 | SN74LS74AN | Texas Instruments | Dual Flip-Flop | SN74LS74A |
| Unknown/None | 1 | SN74LS194AN | Texas Instruments | 4-Bit Bidirectional Shift Register | SN74LS194A |
| Unknown/None | 1 | CD327A-NL | Texas Instruments | ||
| Unknown/None | 2 | MCM6810P | Motorola | 128*8-bit RAM | MCM6810 |
| Unknown/None | 1 | SN74LS32N | Texas Instruments | Quad 2-Input Positive OR Gate | SN74LS32 |
| Unknown/None | 2 | SN74LS367AN | Texas Instruments | Hex Bus Driver | SN74LS367A |
| Unknown/None | 1 | SN74LS03N | Texas Instruments | Quad 2-Input Positive-NAND Gate | SN74LS03 |
| Unknown/None | 2 | SN74LS138N | Texas Instruments | Decoder/Demultiplexer | SN74LS138 |
| Unknown/None | 1 | SN74LS244N | Texas Instruments | Octal Buffer and Line Driver | SNx4LS24x |
| Unknown/None | 1 | CD3226A-NL | Texas Instruments |
Replacement Parts
Power Supply
| RefDes | Qty | Compatible Part Number | Order Links |
|---|---|---|---|
| C7, C10 | 2 | 476TTA016M | DigiKey Mouser |
| C8 | 1 | 108TTA025M | DigiKey Mouser |
| C9 | 1 | 338TTA035M | DigiKey Mouser |
| C12 | 1 | 475TTA050M | DigiKey Mouser |
| C15 | 1 | EEU-FR1V471LB | DigiKey Mouser |
Main Board
| RefDes | Qty | Compatible Part Number | Order Links |
|---|---|---|---|
| C1, C2, C7 | 3 | 107TTA025M | DigiKey Mouser |
| C3 | 1 | 106TTA035M | DigiKey Mouser |
| C4, C5, C6, C8, C9 | 5 | 226TTA035M | DigiKey Mouser |
| RefDes | Qty | Compatible Part Number | Order Links |
|---|---|---|---|
| 1 | RC4558P | DigiKey Mouser LCSC | |
| 1 | SN74LS156N | DigiKey Mouser | |
| 3 | SN74LS04N / SN74LS04N(XBLW) | DigiKey Mouser LCSC | |
| 2 | SN74LS00N / SN74LS00N(XBLW) | DigiKey Mouser LCSC | |
| 1 | SN74LS74AN | DigiKey Mouser LCSC | |
| 1 | SN74LS194AN | DigiKey Mouser LCSC | |
| 1 | DigiKey Mouser LCSC | ||
| 2 | |||
| 1 | SN74LS32N / SN74LS32N(XBLW) | DigiKey Mouser LCSC | |
| 2 | SN74LS367AN | DigiKey Mouser | |
| 1 | SN74LS03N | DigiKey Mouser | |
| 2 | SN74LS138N / SN74LS138N(XBLW) | DigiKey Mouser LCSC | |
| 1 | SN74LS244N / SN74LS244N(XBLW) | DigiKey Mouser LCSC |
If parts are not available or different selection is preferred, you can use the values in the Original Parts section to perform a parametric search.