Differences

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

--- telephony:ta1232_td816_td1232_hw_arch [2025/04/19 20:22] – prppedro
+++ telephony:ta1232_td816_td1232_hw_arch [2025/04/19 23:42] (current) – [Memory] prppedro
@@ 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|}} |
-A0-A23, as well as D0-D15 lanes are distributed all across the system, interconnecting several daughter boards and add-on cards. It seems like all additional hardware connects to this bus one way or another, and the IORN/IOWN lines (connected to the IC2, not the CPU) are to be found in all parts of the system. We have addressing, data and control lines, clearly establishing a system bus architecture.
+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.
-So, the obvious conclusion is that this system is indeed a computer, and a m68k computer at it, albeit a so-called «embedded» one.
-Devices seems to be connected to it in a similar fashion as ISA devices are typically connected to a computer: we have clock, interrupts and addressing to determine how the communication happens on the bus. How exactly is this communication happening is yet to be determined by further examination of the schematics and a healthy dose of reverse engineering with oscilloscopes or ESP8266's. I might update this article with future findings or move the entire thing to a GitHub repository, in the future.
 ===== Caller Identification Card =====

Tadeu's Wiki

User Tools

Site Tools

Differences

Page Tools