larry@morpho.UUCP (Larry Morris) (06/18/91)
I just received the glossy for the TwinCom 96/42 (Hot off the press). The specs are reproduced below. The only REAL significant feature is the $300 price. It is currently available only as an internal, but they told me an external should be out sometime this summer. Has anyone bought one of these? I would be interested in feedback. TwinCom 96/42 Technical Specifications: Rockwell RC9696/12 Data Pump and RC9696AC Chip Set Transfer Rates up to 38,400 bps CCITT V.32, V.22bis, V.22, V.21 modes with automode detect and bell 212A & 103 V.42(LAP-M) and MNP 2,3,4 Error Correction V.42 bis (BLTZ) and MNP data compression Automatic V.42/MNP 4, V.42bis/MNP 5 negotiation Dial Up and Leased line compatible Asynch and Synch Modes Automatic retrain capability Enhanced AT command set Extended MNP commands Speed Buffering and flow control Line quality and received line level monitoring Selectable line impedance matching networks Diagnostics Tests - Remote digital loopback - Remote digital loopback with self test - Local Analog loopback - Local Analog loopback with self test - Power-On self test Adaptive Tone/Pulse dialing Automatic dial, re-dial and answer capabilities inactivity disconnect programmable timer On-board NV-RAM for stored user profiles and four phone numbers Power Consumption: 3 Watts Size: 8 bit PC card 9"x4.5" Phone Jacks: One RJ-45 and 1 RJ-11 Manufacturer: Image Communications Order Line: 800-666-2496 Fax Orders: 201-935-6548 Tech Support: 201-935-8880 I have no interest in Image-Communications, just a very potential future customer. -- Disclaimer: I write device drivers, not company policy. The above opinions are mine, all mine. ____________________________________________________________________________ amc-gw!morpho!larry
wtm@uhura.neoucom.EDU (Bill Mayhew) (06/22/91)
Something to consider is the UART chip. I reviewed GVC v.32 / v.42 v.42bis modems recently. The internal GVC modem uses an 80C450 UART chip which is a 40 pin surface mount device. Given the interrupt structure of the IBM-derived ISA bus, this does not bode well for good performance at high speeds because an interrupt signal will be generated for each incoming character. In the MS-DOS world, you can hand code an assembly level driver to mitigate the effect of receiving a large number of interrupts. With a Unix system, the kernel will be forced to do a context switch to process every interrupt. Even on a 33 MHz '486 system this may require many microseconds and imposes a significant performance penalty. The best solution is to have an external modem, buy a cheap comm board and replace the stock xx450 UART with a National Semiconductor 16550 UART. The 16550 is compatible with xx450, but may be switched to FIFO mode cutting interrput burden by as much as 94%. The Western Digital version of the 16550 has bugs; do not use it. Of course, you have to supply the software driver for your host. Newer comm programs such as Procomm have integral support for the 16550 UART. The other solution is to find out if the xx450 chip is socketed on the internal modem and replace it. The only internal modem I am certain of having a socketed 16450 is the Multitech v.32 modem; it is much more expensive. The GVC modem is available in external form for about $405 in single unit quantities. Bill -- Bill Mayhew NEOUCOM Computer Services Department Rootstown, OH 44272-9995 USA phone: 216-325-2511 wtm@uhura.neoucom.edu ....!uunet!aablue!neoucom!wtm via internet: (140.220.001.001)