Differences

This shows you the differences between two versions of the page.

--- telephony:ta1232_td816_td1232_hw_arch [2025/04/19 20:00] – created prppedro
+++ telephony:ta1232_td816_td1232_hw_arch [2025/04/19 23:42] (current) – [Memory] prppedro
@@ Line 5: / Line 5: @@
 Those units have a lot in common and the schematics I could find seem to confirm they're iterations of the same project, even though TA1232 has important differences, like not supporting digital proprietary phones.
-===== CPU =====
+===== CPU and general architecture =====
 The CPU is a classic 68k chip. My unit, particularly, uses a TMP68301AF-12 CPU. According to the [datasheet](https://datasheet4u.com/pdf-down/T/M/P/TMP68301AF-12-Toshiba.pdf), it's based in the 68HC000 core, produced by Toshiba. It's a 16-bit processor, with 24 addressing lines and 16-bit wide bus.
@@ Line 11: / Line 11: @@
 {{ :telephony:toshiba_tmp68301af-12_cpu.jpg?400 |}}
-While the CPU might be different between versions (newer models do operate at 12 MHz, in contraposition to older models at 8 MHz), the pinout seems to be largely the same in all three versions.
+While the CPU might be different between versions (newer KX-TD models do operate at 12 MHz, in contraposition to older models at 8 MHz), the pinout seems to be largely the same in all three versions.
 ^ KX-TD1232CE/1232BX etc.               ^ KX-TD816E (UK)                      ^ KX-TA1232                                                                     ^
 | {{ :telephony:cpu_td1232ce.png?280|}} | {{ :telephony:cpu_td816e.png?280|}} | {{ :telephony:cpu_ta1232.png?280|}} |
+This PABX is, in fact, a simple, embedded m68k computer. Memory and peripherals are addressed directly, there's no MMU. Also, albeit the system has a 16-bit wide bus, it looks like only the memory chips are using all those lines (see diagram below.) All other devices I saw were using only eight lines of the data bus. Addressing lines seems also to go under-used for most devices, e.g. expansion cards using A1-A5, or even the Caller ID card, using A1 and A5, ignoring all others.
+===== Memory =====
+{{ :telephony:rom_ram_rtc_td1232ce.png?600 |}}
+{{ :telephony:ram_not_mounted_ta1232.png?400|}}
+Those systems seem to be typically equipped with four RAM and two ROM chips. TA1232's Service Manual seems to suggest they might not be always populated. On my TD816BX, [[telephony:td816bx_hardware|they are]]. Since this is a purpose built embedded computer, rather than a general computer, we got SRAM chips soldered to exactly the number of lines they need, without room for larger chips.
+I couldn't ascertain why the heck we have two small 32K chips as the first two SRAM IC's, although I find quite interesting the fact that the configuration dump does result in a file that's approximately 64 KB in size, and I remember reading somewhere that those systems hold the configuration in the SRAM's. How this is holding up after all those years scapes me, but the battery I thought to be specific to the RTC may have something to do with this.
+===== Caller Identification Card =====
+As this investigation progresses, I might transfer this section to it's own article, since it's a bit of a rabbit hole.
+The digital PABX's (KX-TD) got the KX-TD193 or TD193X as their standard Caller ID add-on card. This part features pretty standard FSK modems that output serial date for two serial-to-parallel converters, that then feed data to the system bus.
+Funnily enough, there's a second card for KX-TD systems called KX-TD193DX, that also does DTMF (hence the extra «D» in the name, I guess), and this card also happens to be nearly identical to the TA-123293 card, which also had DTMF decoding facilities. The only significative difference I could spot was an extra IC, which communicated with TA1232 via four extra pins that KX-TD's don't have.

Tadeu's Wiki

User Tools

Site Tools

Differences

Page Tools