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tymcom-x [2017/11/28 09:58]
jms [Hardware] |
tymcom-x [2022/05/12 07:42] (current)
lars [Connection to the network] Host-Base interface emulation. |
| ==== Connection to the network ==== | ==== Connection to the network ==== |
| |
| TYMCOM-X (the PDP-10 system as a whole) doe not connect to TTYs (other than the Console). Instead, a Tymnet Node (known as a Base) does DMA to two circular buffers (IRING and ORING) in the PDP-10's memory. The Base is connected by synchronous serial links to two or more Tyment Nodes using the T201 (Tymnet II) Node Code protocol. The nodes are indirectly connected to the Tymnet Supervisor, which is responsible for creating login circuits (known as Needles when they reach their destination). | TYMCOM-X (the PDP-10 system as a whole) doe not connect to TTYs (other than the Console). Instead, a Tymnet Node (known as a Base) does DMA to/from two circular buffers (IRING and ORING) in the PDP-10's memory. The Base is connected by synchronous serial links to two or more Tyment Nodes using the T201 (Tymnet II) Node Code protocol. The nodes are indirectly connected to the Tymnet Supervisor, which is responsible for creating login circuits (known as Needles when they reach their destination). |
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| The Base-Host protocol is based on the Tymnet Circuit protocol, but designed to be delivered as 32-bit messages over a parallel connection. The KI-10 and KL-10 systems had an EBUS slot (M68000 based) storing data left justified in a 36-bit word, with all ones in the unused low-order 4 bits. The KS-2020 systems had a PDP-11/23 known as a microTymSat using the 16-bit DR-11 parallel interface going into a DR-11 plugged in to the 2020's low-priority UNIBUS. The data from the DR11 is processed by a KMC11 and stored right justified in two 18-bit halfwords. When the KMC11 is used, the KS needs special microcode to implement UUILDB and UUIDPB to process bytes. When the KMC11 is not used, data is left justified just like the KL. | The Base-Host protocol is based on the Tymnet Circuit protocol, but designed to be delivered as 32-bit messages over a parallel connection. The KI-10 and KL-10 systems had an EBUS slot (M68000 based) storing data left justified in a 36-bit word, with all ones in the unused low-order 4 bits. The KS-2020 systems had a PDP-11/23 known as a microTymSat using the 16-bit DR-11 parallel interface going into a DR-11 plugged in to the 2020's low-priority UNIBUS. The data from the DR11 is processed by a KMC11 and stored right justified in two 18-bit halfwords. When the KMC11 is used, the KS needs special microcode to implement UUILDB and UUIDPB to process bytes. When the KMC11 is not used, data is left justified just like the KL. |
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| The Base uses a pointer in low memory (IRP620) to write data into the IRING, then update the IRP620 modulo the ring size. The PDP-10 uses its pointer (IRPPDP) to read the IRING whenever the pointers differed. These characters would go into SCNSER's TTY chunks, to be processed at clock level. Output from the PDP-10 would first to into SCNSER's TTY chunks, and from there to the output buffer (ORING). It updates its pointer (ORPPDP) and the Base reads from the ORING whenever its pointer (ORP6200) fell behind. Transfers occurred 60 times per second, but each transfer could include many characters from many lines at once. | The Base uses a pointer in low memory (IRP620) to write data into the IRING, then update the IRP620 modulo the ring size. The PDP-10 uses its pointer (IRPPDP) to read the IRING whenever the pointers differed. These characters would go into SCNSER's TTY chunks, to be processed at clock level. Output from the PDP-10 would first go into SCNSER's TTY chunks, and from there to the output buffer (ORING). The PDP-10 updates its pointer (ORPPDP) and the Base reads from the ORING whenever its pointer (ORP620) fell behind. Transfers occurred 60 times per second, but each transfer could include many characters from many lines at once. |
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| | Cornwell's KI10 emulator now has bare-bones support for the Base interface as used on SUMEX-AIM. |
| | See https://github.com/rcornwell/sims/blob/master/PDP10/kx10_tym.c |
| ==== Host-Base protocol ==== | ==== Host-Base protocol ==== |
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| ==== Other pages ==== | ==== Other pages ==== |
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| [[tymcom-x|Overview]] page, [[tymcom-x-simh|SIMH Setup]] page, [[tymcom-x-startup|TYMCOM-X Startup]] page, [[tymcom-x-status|Status]] page. | [[tymcom-x|Overview]] page, [[tymcom-x-simh|SIMH Setup]] page, [[tymcom-x-startup|TYMCOM-X Startup]] page, [[tymcom-x-tape|TITO on disk]] page, [[tymcom-x-status|Status]] page. |
